Preliminary Report No. 12
ITALIAN ARMOURED CAR
AUTOBLINDA 40
Egham
May 1943
FOREWORD
The car arrived in this country in good condition. This is accounted
for by the comparatively small mileage covered, and by the
considerable trouble taken to protect components from corrosion or
damage during transit. After a few minor adjustments the car was made
a runner, and mechanically it appeared to be fairly sound with the
exception of the steering which needs some attention. Our observations
on the performance are in no way intended to constitute a field trial
as this is to be carried out by F.V.P.E. at a later date. However, as
the result of a brief run, a few observations with regard to the
handling and performance of the car are given later in this foreword.
Mechanically the car has many interesting and certain commendable
features. The distributed drive to all four wheels and the four wheel
steering, make it possible to use a single differential at the expense
however of a very large number of bevel gears. The effect of
variations in angular velocity of the wheel, due to the cross-pin type
universal joint, is very considerably minimised by the hub reduction
gear, and further by the four wheel steering which allows a reasonable
turning circle to be obtained with a small angular wheel movement. If
one can assume that this arrangement is satisfactory, the absence of
four constant velocity universal joints constitutes a very
considerable economy in manufacture. The five speed gearbox and
overdrive gear, giving six forward speeds, gives a wider range than is
usual in Armoured Car practice. A directional control lever reverses
the whole transmission and allows the rear driver to use the first
four speeds. Thus the car may be driven in either direction.
The wheels are not easily removable but detachable rims are fitted.
Two spare rims are carried on either side of the hull and are mounted
on hubs which are free to revolve. The tyres on the spare rims are
therefore able to take the weight of the car to avoid bellying over
very rough country.
Of the engine very little can be said, as in the interests of time,
and in view of the forthcoming running trials it was not considered
advisable to dismantle this unit. Externally it appears to be fairly
orthodox and the estimated power given on page 11 should be taken as
being very approximate, as neither the capacity nor speed range are
Known. Access to the engine is difficult, and the tubular chassis
cross member which passes over it would appear to be decidedly
inconvenient when removing or replacing the unit.
While the general mechanical layout appears to have been well thought
out and designed specifically for the job, the mechanical details in
certain cases contrast strikingly in their inadequacy or shoddiness.
The whole construction and layout of the rear driver's section savours
of modification or after-thought. The main petrol tank under the floor
is only protected by a light gauge tray and is extremely inaccessible.
The forward tank feeds into the main tank by gravity and no stop cock
is provided in the line. There are other similar examples of bad design.
The electrical equipment is generally of good quality. The
inter-communication equipment appears to be an aircraft installation,
the various units being marked "REGIA AERONAUTICA." The dynamo seems
to be much smaller than would be required for the size of batteries
carried, and may not be the original. No fuses could be found and it
is assumed that the circuits are unprotected, which is rather surprising.
With regard to the armament and armour, it is noticeable that again
the lack of attention paid to detail design considerably reduces the
potency of the car as a fighting vehicle. The one man turret does not
conform to the latest British requirement for a three man turret. The
exposed traverse gears, the awkward position of the 2 cm. cocking
handle and the limited observation in the turret are in our opinion
decidedly undesirable features. There is no electrical equipment in
the turret and consequently no rotary base junction. The commander is
therefore faced with the problem of what to do with his headphone and
microphone leads when traversing the turret.
It is impossible to sight the rear hull gun when it is fully depressed
and extremely difficult to do so at any angle under zero. The gunners
seat is not in line with the gun and he must lean awkwardly in order
to sight when the gun is traversed left. His back is fouled by the
turret gunners seat when the turret is straight ahead or traversed
left. These points and the improvised appearance of the gun mounting
suggest the possibility that the rear hull gun was added as an
afterthought. The wooden ammunition racks are very roughly
constructed. In general, splash protection is noticeable by its
absence. A desirable feature on the other hand is the clean belly of
the car and for this reason it is thought that its ability to cross
wire obstacles may be good.
As the result of a brief cross country and road run the following
points were noted with regard to the handling and performance. Owing
to the defective steering which caused very severe "shimmying" at
speeds over about 20 m.p.h. it was not possible to drive above this
speed.
The engine pulled fairly well at slow speeds and from the front
driving position was mechanically quiet especially in view off the
fact that no bulkhead is fitted. Engine fumes were barely noticeable
in the fighting compartment when driving forward, but were decidedly
objectionable when in rear control. There did not appear to be any
tendency for the engine to overheat in rear control although very
little running was done in this direction.
The first four gears are noisy and the change is extremely slow. The
absence of a clutch stop makes upward changes on rising ground
difficult. The direct and overdrive gears, fifth and sixth, being of
constant mesh, are much quieter and the change is, of course, is much
quicker. The change from front to rear control is simple to effect
from the front driving position and if the normal gear lever is in
neutral, the clutch need not be used. From the rear driving position,
however, the directional control lever is so situated that it is
almost impossible to operate it.
At low speeds the steering was reasonably light by virtue of the fact
that it is extremely low geared. As there is absolutely no
self-centring action when driving in either direction, it is assumed
that there is no castor angle. At about 15 mph there was a tendency to
"shimmying" which increased in violence unit at about 20 m.p.h. the
car was almost uncontrollable. It is considered that, although this
defect is obviously an abnormal state of affairs, the apparent lack of
castor angle may aggravate this tendency.
The hydraulic brakes were quite light to operate, but not very positive.
The independent suspension was excellent over both road and cross
country and although extremely soft it did not appear to cause any
undue degree of rolling or pitching at the fairly slow speeds which
were attained.
The front driving position is quite comfortable, but the rear driving
position is impossibly cramped for a tall man. The lack of any side
vision is a decided disadvantage.
The car was driven into a small muddy depression of clay and became
completely bogged even though the differential was locked. There was
no question of clutch slip or of insufficient engine power as all four
wheels were turning. It is not considered that most other four wheel
drive vehicles would have become bogged under similar conditions, and
the fact that the car was shod with comparatively smooth "Libia" tyres
may have been partly responsible for this rather surprising failure.
In conclusion it may be said that the general impression is that the
basic design has been well thought out with a view to producing a
manoeuvrable high speed fighting vehicle, but that certain detail
design features particularly with regard to the fighting arrangements
have received such scant attention that the potential possibilities
have not been fully realised.
PRELIMINARY REPORT
ON
ITALIAN ARMOURED CAR
AUTOBLINDA '40'
(Received from Middle East)
EXAMINED AT CHOBHAM (D.T.D. No. 3004) D.T.D. PROJECT NO. V.7021. May,
1943 EXAMINERS : MAJOR J.D. BARNES, R. T. R., and MR. D.M. PEARCE,
B.A. (Cantab).
I. TYPE
ABM '40' 4 x 4 armoured oar. Chassis No. 40788. Year: 1941.
2. IDENTIFICATION MARKINGS
The figure "8" appears in black paint on upper nearside hull plate and
on the upper offside hull plate and the nearside front wing. A
pennant, black over red, with a crescent moon and two palm trees
superimposed is also painted on the upper offside hull plate. The
words "Polish Carpathian Lancer" are painted in black on the upper
nearside hull plate.
3. GENERAL CONDITION
The general condition of the vehicle appears to be good and the total
distance recorded on the speedometer is only just over 4,000 miles.
Only a few minor adjustments were necessary to make it a runner. The
tyres on all four wheels are slightly worn, but those on the two spare
rims appear to have had little use.
4. WEIGHT
As received and partially stowed:
Total 6.9 tons.
Front Wheels: 3.05 tons.
Rear Wheels : 3.85 tons.
Estimated total weight in battle order : 7. 5 tons.
5. SPEED
Not tested. Speedometer shows maximum speed in 6th gear as 78.5 K.P.H.
(49 m.p.h.). This figure indicates forward speed. The highest ratio
which can be engaged by the rear driver is 4th and the maximum speed
in this gear is indicated as 38.5 K.P.H. (24 m.p.h.) on the speedometer.
6 CREW
Four: Commander/Gunner, two drivers (one fore and aft) and a rear
hull gunner.
7. DIMENSIONS
LENGTH 17' 1½ "
WIDTH 6' 4¼"
HEIGHT 7' 11 5/8"
CLEARANCE 13 ½" (under hull)
CLEARANCE 10 ½ " (under spare rims)
WHEELBASE 10' 7¾ "
TRACK 5' 6 ½"
8. ARMAMENT
Turret Guns
2 cm. Breda.
Markings: "Canone da 20 M/M Controaereo - Mod.1935
No. 3809 Brescia 1940 - XVIII - "
Total Weight: 150 lb.
Total Length: 80 ins.
Weight of Barrel: 6I lb.
Length of Barrel: 57 1/2 ins.
The gun is gas operated and the regulator has ten positions. It is fed
by plate chargers, each charge holding 8 rounds. The feed is from the
left hand side and the empty cases are returned to the plate which is
ejected to the right. A safety catch is provided on the firing handle
and a buffer adjustment on the rear cross piece. A flash eliminator
consisting of a plain cylinder 6 3/8" long and 1 3/4" bore is fitted.
8 mm. M. G. Breda.
Markings: "8 mm. Metragliatrice Breda
Mod. 38 - No.157. 30.XVII"
Total Weight: 55 1/2 lb.
Total Length: 35 3/4 ins.
Weight of Barrel: 11 1/4 lb.
Length of Barrel: 23 3/8 ins.
The gun is gas operated and is fed by spring loaded 24 round magazines
of the Bren type. A safety catch is situated on the rear cross piece.
The barrel can easily be removed.
Traverse. 360 deg - Both guns traverse with the turret and particulars
of the traversing gear will be found on Page 8, Para II.
Elevation. Maximum Elevation: 18deg Maximum Depression: 9deg
The elevating gear is operated by a handcrank on the left of the
gunner. The handcrank has a radius of 3 1/4" and rotates on a
transverse axis. Fourteen and a half turns of the crank are required
from full depression to full elevation. The movement of the handcrank
is transmitted through a worm to a phosphor bronze sleeve which
rotates in a vertical plane in the elevating gear-box. This sleeve has
a square female thread to suit a male member, the forked end of which
swivels in a mounting bolted to the turret roof.
Gun Mountings.
The 2 cm. gun mounting is of channel section, semi-circular extensions
of the sides at the forward ends forming a bearing to carry lugs on
which the gun is mounted.
The lugs are slotted across their inner faces to suit keys on the gun.
Pins located in coincident holes in the mountings, and the lugs,
secure the latter, and the withdrawal of these pins permits the lugs
to be pulled clear of the gun, thus providing a quick and simple
method of mounting or dismounting the gun. To facilitate the
withdrawal of the lugs, eye-bolts are screwed into their outer ends.
At the rear of the mounting the gun is secured by a single pin.
The M.G. mounting consists of two separate brackets bolted to the main
mounting on the left hand side. The rear member is of orthodox slide
pattern and the gun is secured to the front member by a locating pin.
Cocking Gear
The cocking gear for the 2 cm. gun is between the right side of the
gun mounting and the telescope tube. The cocking piece is secured to a
slide which travels in guides and in a slot machined in the side of
the mounting. This slide is secured to a single roller chain which is
fitted to sprockets mounted alongside the gun mounting. The rearmost
sprocket is turned by a handcrank of 4 3/4" radius - three turns of
the crank being necessary to cock the gun. A clock spring housed in a
drum through which the crankshaft passes is wound as the cocking piece
is drawn back. When the gun is cocked, the crank handle, which is
hinged, is swung back and by this action the crank is disengaged and
the cocking piece returned by the spring. It is worthy of note that
when the hand-crank is at the point nearest to gunner it can only be
turned with difficulty by a normally proportioned man owing to lack of
clearance between the man's body and the crank. The distance between
the crankhandle and backrest at this point is 9" with gun in
horizontal position. This difficulty exists throughout the full arc of
elevation and depression. In the latter case, the handle is
uncomfortably close to the gunner's face which constitutes a source of
danger should the handle be released before being dis-engaged from the
return spring.
Sighting
Telescopic : Field: 30 deg Magnification: 1
Length of Telescope: 32 5/8"
Weight with brow pad: 14 lb. 7oz.
Markings : CANNOCCHIALE DI PUNTAMENTO
CAMPO 30 deg - ING 1 x SAN GEORGIO S.A.I.
GENOVA - SESTRI
No. 88215.
The telescope is housed in a tubular member bolted to the right hand
side of the gun mounting. The instrument is a straight tube type with
an articulated eyepiece and brow pad. There would appear to be no
"zeroing" device fitted. Firing.
Both the 2 cm. and the co-axial M.G. are fired by foot control. Pedals
are mounted on either side of a central tubular support which is taken
from a triangular bracket bolted to the turret flange under the gun
mounting. The "pull" is transmitted to the triggers on the guns
through "Bowden" type cables. A "tee" type footrest is fitted to the
central support, immediately over the firing pedals and a further
footplate is provided behind and below them.
Gunner's Seat.
The turret gunner's seat is mounted on two tubular supports bolted to
the turret flange and rotating with it. The seat is hinged to the
supports and when not in use it is automatically folded back by coil
springs incorporated in the hinges. A body strap is provided to
prevent the gunner being unseated when travelling over rough country.
The seat is adjustable for height allowing a range of 4". The
adjustment is not a quick one and necessitates the loosening of two
nuts on the clamps securing the seat to the supports. A padded back
rest, also bolted to the turret flange, is provided.
Hull Gun.
The gun is a similar weapon to that mounted in the turret.
Markings: METRAGEL BREDA TIPO C.A. CAL 8.
No. 2458 - 41 -XIX.
Traverse and Elevation:
Traverse 28 deg
Maximum Elevation 14 deg
Maximum Depression 7 deg
The traverse and elevation of the gun are by hand. The mounting may be
clamped at any point in the arc of traverse by tightening a wing nut
on a screw projecting from the outer cup about which travels a slotted
quadrant which is screwed to the traversing ring.
A leather strap hanging from the roof provides a means of steadying
the gun when it is not in use.
Gun Mounting.
The mounting which is of "Gimbal" type consists of four main members,
a stationary ring bolted to the hull in which the assembly is mounted,
an inner ring which swings in a vertical axis and an inner hemisphere
moving about a horizontal axis which forms the mantlet. The inner
hemisphere is 15 mm. thick. The fourth member of the assembly is the
gun mounting which is of orthodox slide and locating pin type. The
mounting is bolted to the inside face of the inner hemisphere. To
allow clearance for the magazine when the gun is loaded it has been
necessary to cut a suitable opening in the hull roof and a domed cover
10 mm. thick and 6" high is bolted over this opening.
Sighting
Telescopic: Field 20 deg Magnification 1
Length of telescope 20 ins. Weight with browpad 5 lb. 5 oz.
Markings: CAMPO 20 deg - ING 1x
SAN GEORGIO S.A.I.
GENOVA - SESTRI
No. 100293.
The telescope is a straight tube type and is mounted on the left of
the gun. There would appear to be no "zeroing" device fitted.
Firing.
The gun is fired by its own hand trigger and only the single hand
control is provided.
Gunner's Seat.
The gunner is provided with a hinged seat mounted on the hull floor.
His position is decidedly uncomfortable and he must lean awkwardly to
the left to place his eye to the sighting telescope.
9. AMMUNITION CARRIED. (See Fig.3)
2 cm. - 344 rounds.
Racks are fitted in the fighting compartment to accommodate 43 plate
chargers each containing 8 rounds of 2 cm. ammunition. Fourteen of
these are carried on the offside and 29 on the nearside. The racks are
of wooden construction and there is a separate compartment to hold
each magazine in horizontal position. A strip of spring steel with a
step riveted to its outer end is fitted to each end of each
compartment to retain the magazines in position. Canvas curtains are
fitted to the front of each tier of compartments.
8 mm. - 2040 rounds.
Stowage for 85 magazines each constructed to hold 24 rounds of 8 mm.
ammunition is provided by wooden racks fitted to the sides of the
fighting compartment. There are 40 compartments on the offside and 45
on the nearside. The magazines are carried in vertical position and a
brass strip screwed along the front of each row of racks and
projecting slightly over the edge of the shelves serves to hold the
magazines in place.
The wooden racks in all cases are of very flimsy construction and it
is doubtful if they would stand up to their load over hard going. The
fire risk occasioned by the use of wood cannot be overlooked.
10. ARMOUR
Details of armour thicknesses and angles will be found on drawings
appended. The general construction is of flat plates bolted together,
although a small amount of plate forming has been used in visor flaps,
ventilating cowls, hatch covers and wheel arches. The bolts are
countersunk and have conical heads. They are generally of 10 mm.
diameter and spring washers are used very largely but not throughout.
Where riveting has been used, the rivets are flush with the outside
surface of the plate.
The fitting of the plates is generally bad, and even in such exposed
positions as the nose, considerable gaps occur between the plate
edges. Very little attempt has been made to protect the crew against
bullet splash. Turret ring protection is provided only at the rear by
a length of 6 mm. angle section bolted to the top plate.
Approximate Brinell hardness figures were obtained with a "Poldi"
portable tester for the main plates of the hull and turret.
In all cases tested the armour was found to be homogeneous of
approximately 320 - 340 Brinell hardness number, with the exception of
the turret front plate. This plate is cast and has a Brinell hardness
number of approximately 197.
II. GENERAL CONSTRUCTION
Chassis.
The channels of the side members face outwards The frame is braced by
a channel section cross member at each end, and by two further cross
members which also serve to carry steering boxes and the lower radius
arms of the suspension units. A tubular bridge of 3" diameter braces
the frame at each end at the point where the suspension units are
mounted.
Hull.
The contours of the hull may be readily seen from the photographs and
drawings appended. It is constructed almost entirely of flat plates
butt jointed over strips of flat or angle section to which they are
bolted or riveted. The hull is bolted to the chassis frame and a
laminated packing material is used in the joint.
There is no belly tray fitted but the power plant and transmission
units are protected by three trays. The rear petrol tank, petrol
filter, radiator header tank and rear driver's instruments and
steering column are mounted on a light channel section framework of
welded construction. The base is bolted to the chassis frame, and the
top to the rear engine cover plate and to the tubular cross member of
the chassis. Mudguards are fitted over each wheel and are bolted to
the hull.
Turret.
The turret is in the form of an octagonal truncated pyramid and is of
bolted construction. Internal Dimensions :
Turret Ring Diameter....3' 2¼" Width at Base ....3' 9"
Front to rear at base...3' 9" Width of Mantlet..11 8½"
Height of Turret........1' 9"
Headroom (from floor of fighting compartment to turret roof) 6' 6 5/8"
Turret Traverse.
Traverse of 360 deg is provided. The floor does not rotate but the
gunner's seat and footrest are suspended from and move with the
turret. The traversing gear is bolted to the turret flange on the
right of the gunner. It is operated by a handwheel of 3 1/4" radius
through bevel gears, a worm and wheel and a pinion to turret ring.
Ninety five turns of the hand-wheel are necessary for complete traverse.
The bevel gears, pinion and roller are entirely exposed and constitute
a source of danger through clothing or other matter becoming entangled
with them. A lock is provided in the form of a spring loaded plunger
engaging splines on the handwheel shaft. No free turn of the turret is
provided. "G" clips may be adjusted by means of wing nuts. The
tightening of these clips whilst not forming a positive lock against
the operation of traverse gearing, prevents movement through backlash
in the gearing during travelling. When the clips are loose there is a
tendency for the turret to jump when the vehicle is travelling. When
the turret guns are depressed the 2 cm. gun mounting fouls the dome in
the roof of the hull which is provided to clear the magazine on the
hull M.G. Consequently the turret cannot traverse completely with the
guns in this position.
Gun Mantlet. The turret gun mantlet is of semi-cylindrical
construction, the thickness of the plates used being 9 mm. The
circular cheeks are bolted to the curved front plate through angle
section riveted to the latter. The cheeks form the bearings for the
trunions on which the mantlet pivots. The front plate of turret is a
single casting and forms a mounting for the mantlet. No protection
against splash is provided either inside or outside
12. OBSERVATION
Forward Driver's Visor.
A vision port for the forward driver is mounted in the front vertical
plate and is offset 5" from centre line. The opening measures 19½" x 6
7/8". A non-slitted hinged B.P. flap is fitted and is operated by a
tubular lever on the right of the driver. Three positions of opening
and one locked position are permitted and the flap is secured in these
positions by the engagement of a pawl in a quadrant. The pawl is
disengaged by pressure of a spring loaded plunger which passes through
the lever. A swivel bolt is fitted at each end of the visor presumably
to secure a glass which is deficient. Above the visor, the front
vertical plate and top plate are cut away to form an opening for an
episcope. This opening is cut 2" down in the front plate and 2" back
in the top plate and is 8" wide. The episcope mounting incorporates a
roller shutter which may be used to close the port when the instrument
is not in its mounting. The episcope is deficient.
Rear Driver's Visor.
The driver at the rear of the vehicle is provided with an identical
visor to the forward driver. It is situated on the nearside of the
rear vertical plate. No provision is made for an episcope for this
driver.
Commander's Vision.
Periscopic: Field 300 Magnification 1
Height of periscope: 16"
Weight with browpad and mounting 16 lb. 4 oz.
Weight of periscope only 71b. 8 oz.
Markings : CANNOCCHIALE PANORAMICO DI OBSERVAZIONE
CAMPO 30deg ING. 1 x
SAN GEORGIO S.A.I.
GENOVA - SESTRI
No. 94951
The periscope is mounted under a domed cover on the nearside of the
turret roof. The instrument operates on the dial sight principle and
has a stationary eyepiece. The object prism is easily removable and
the whole instrument may be readily dismounted and stowed. In order to
guide the user as to the direction of vision the following inscription
is engraved on the eyepiece screen:
AVANTI (Front) DESTRA (Right)
DIETRO (Back) SINISTRA (Left)
Revolver Ports.
A revolver port is fitted in the top plate of each side door and in
each turret side plate. The construction of the ports is shown in fig. 6.
13. ACCESS DOORS AND ESCAPE HATCHES
Hull.
Access to the hull is obtained by a halved door on each side, situated
slightly forward of the centre. The lower half of each door is hinged
to the lower hull side plate and the upper half to the upper side
plate. The top half of the openings covered by these doors is
rectangular and measures 1' 6" x 1' 6¼" whilst the lower half is in
the form of a trapexium measuring 1' 6" at the top, 10½" at the bottom
and 1' 6¼" in height.
The doors are of 10 mm. plate and a lip is formed on the lower edge of
each upper half door to overlap the upper edge of the lower half which
is chamfered to suit. Each half door is secured by a casement type
catch, the spindle of which passes through the door in a spring loaded
boss. The catch locates in a quadrant fitted to the side plate and in
order to release the catch it is necessary to push inwards and turn a
lever from the outside or to pull and turn a handle on the inside.
A barrel bolt is fitted to the inside of the upper half of each door
to allow the crew to prevent the doors from being opened from the
outside. Staples are fitted to the outside of each pair of doors and
to the hull side plates to accommodate padlocks.
The hinges incorporate limiting stops to avoid damage to the catches
by contact with the hull side when the doors are opened.
Turret.
There is an escape hatch in the top of the turret measuring 1' 8½"
wide and 1' 3¼" from front to rear. This hatch is offset 4¾" to the
offside of the turret. It is provided with a cover hinged to the front
and is secured by two latches similar to those in the side access
doors. A lip formed at the edges of the cover locates over a splash
ring riveted to the turret top.
A circular aperture of 4" diameter is provided in this door. A sliding
B.P. cover is provided and is secured by a handnut.
A loading hatch for mounting the 2 cm. gun is provided in the rear of
the turret and measures 14¾" x 14". A B.P. door hinged to the top is
fitted to this hatch. This door is locked by two bolts which are
actuated by a pinion engaging in racks at ends of bolts. The operation
is by lever on the inside of the door, which cannot be opened from the
outside.
Engine Cover Plate Hatches.
Two hatches of trapezoidal plan each measuring 36" x 14" x 10" provide
access to the engine. They are hinged to the centre. These covers are
louvered for air inlet and each is secured by 3 brass swivel bolts
hinged to engine cover plate.
Head Lamp Flaps. (See Fig 5)
The front head lamps are recessed in the front vertical plate and may
be completely covered by B.P. flaps. These flaps are hinged at the top
and may be opened or closed by the forward driver, each flap having a
separate lever and spring loaded pawl engaging a quadrant.
14. ENGINE
Maker. S.P.A.
Type. 6 cylinder in line
Fuel. Petrol
Markings. S.P.A. 518931 21-11-40 Abm.1. 100041
Rating.
(See Foreword) capacity not measured. Estimated maximum B.H.P.
approximately 100 - 120.
Valves.
There are two overhead valves per cylinder mounted in three separate
heads. The valves are push-rod operated through rocker arms and
clearance is adjusted by square head set screws at end of rocker arms.
The rocker shaft in each head is mounted in two bearings. Double valve
springs are employed and caps are fitted to ends of valve stems. The
springs are retained by split cones. Three aluminium rocker-box covers
are fitted, one for each head, each incorporating a gauze breather
under which is a baffle plate.
Fuel Capacity.
Three petrol tanks with a total capacity of 46 gallons are fitted as
follows :
One under floor of fighting compartment with a capacity of 26.5
gallons, the filler cap for which is situated forward on upper
nearside hull plate. A second fuel tank is mounted in steel straps in
scuttle formed by front glacis plate, immediately. over driver's
knees. This tank has a capacity of 12 gallons. The filler cap is
mounted on the top of the tank and is accessible through the glacis
plate on removal of a cast B.P. domed cover. A third tank is mounted
in steel straps on the offside of the rear scuttle formed by the
engine cover plate. The capacity of this tank is 7.5 gallons and its
filler cap is at the top of the tank and is accessible from the inside
of the vehicle.
Petrol Pumps and Fuel System.
Two electric diaphragm type petrol pumps are mounted alongside the
main fuel tank underneath the floor of the fighting compartment. The
circuit is controlled by the ignition switch. Their output is coupled
and the fuel is conveyed via a single copper pipe, a two-way cock and
a bowl type filter mounted under the rear petrol tank to the
carburettor. The filter is marked: "ZENITH - TORINO". The fuel in the
forward tank is fed by gravity to the main tank. The small tank at the
rear contains the reserve supply of fuel which is fed to the
carburettor by gravity via the two-way cock in a position between
reserve and normal.
There is no inscription to indicate that this constitutes "OFF"
position. The two positions marked being
"Reserve" and "Normale."
A priming cock is provided for each cylinder. These are mounted on
near side of the engine below the sparking plugs.
Carburettor.
Of up-draught type and mounted on off-side of engine under exhaust and
inlet manifold.
Exhaust.
The exhaust manifold is on the offside of the engine. A cylindrical
silencer is mounted on the hull side.
Air Cleaners.
There is a dry type air cleaner mounted low down on the offside of the
engine at the flywheel end. Its element is accessible through the
fighting compartment, a wing nut being provided for its removal.
Ignition.
A Marelli magneto is mounted low down on the nearside of the engine
and is driven off the timing gears through an enclosed shaft and a
metal vernier type coupling. The magneto is fully screened to prevent
radio interference. An impulse starter is incorporated in the magneto.
The plug leads are also fully screened by a braided metal sheath and
are carried through a tubular metal support to six 14 mm. Marelli
three point sparking plugs. The centre electrodes of the plugs are
enclosed and the leads are secured by means of shouldered nuts which
contact the leads with the electrodes.
Dynamo.
A Magnetti Marelli dynamo is mounted forward on the offside of the
engine and is driven from the timing case through a shaft and roller
chain type flexible coupling.
Voltage Control.
The dynamo voltage is controlled by a vibrating contact type
controller mounted to the right of the rear driver's panel, and a
cut-out is fitted in the same case. A small box carrying a 12V 5W lamp
and switch is mounted underneath the control unit, the lamp being
connected to terminals marked +D and +Q (dynamo positive and battery
positive) which would indicate that this lamp is a warning lamp for
the rear driver.
Starters.
A manual starting handle is provided which engages a dog at the end of
the crankshaft. An orifice is provided for the starting handle in the
tail plate, a screwed cap being fitted for protection. An electric
starter, solenoid operated, is mounted on the offside of the engine.
It is of the orthodox type with Bendix pinion type of engagement.
Accumulators.
The accumulator consists of four 6 V batteries of Marelli manufacture.
They are housed in pairs on each side of the vehicle in steel boxes
under the floor of the hull and on the outside of the chassis members
immediately beneath the hull doors. To obtain access to the batteries
is a lengthy and somewhat difficult task. It necessitates removal of
two stowage boxes on either side of the hull, in addition to removal
of a large portion of the floor plates. Numerous bolts and setscrews
are involved, many of which are themselves inaccessible. It is
probably for this reason that the acid level in all accumulators was
found to be low and that considerable corrosion had occurred at the
terminals. Further points of interest are that there are no drain
holes in the carrier boxes. Consequently spilled acid tends to cause
corrosion here. The faces of the rubber mats laid across the top of
the accumulators to insulate them from the floor plates become wet
through condensation and their efficiency as a di-electric is
considerably reduced. There is no ammeter in the circuit.
Governors.
A centrifugal governor driven in line with the dynamo is fitted, but
is not connected to the carburettor, the connecting lever having been
secured to the case of the unit by a sealed wire.
A suction type governor is incorporated in the carburettor but is not
in operation owing to damage to adjusting screw from the butterfly,
which is presumably held in the full open position.
Cooling.
Water; radiators (sealed system), centrifugal pump and two fans.
Radiators.
Two radiators are mounted vertically side by side at the rear of the
engine compartment. An independent header tank with a capacity of 2.5
gallons is mounted on the near side of the rear scuttle in steel
straps. The filler cap is at the top of the tank on the inside of the
vehicle. The matrix of each radiator is constructed in six sections,
each section consisting of a bank of tubes coupled to its neighbour by
a double banjo type union at the top and bottom.
Water Pump.
A centrifugal water pump is driven in line with the dynamo and governor.
Fans.
Two aluminium radial flow fans are mounted in a bulkhead at the rear
of engine in front of radiators. They are driven from the crank shaft
at engine speed by single Vee belts.
Air is taken through louvers, in the rear engine cover plate and,
having passed over the engine, is exhausted by fans through the
radiators and louvers in the upper tail plate and an opening in the
lower tail plate which is protected by a B. P. cowl.
Vibration Damper.
A large Lanchester type vibration damper is mounted behind the fan
drive pulley.
Lubrication.
Lubrication is by forced feed, the sump being dry. An oil canister is
mounted on the nearside of the engine. The filler cap which
incorporates a dipstick is situated on top of the canister and is
accessible through the nearside engine cover plate hatch. A further
cap marked SCARRICO OLIO (Used Oil), on top of the canister gives
access to a remote controlled drain plug. The plug is opened by
turning a square section rod which is carried through the canister to
the aforementioned cap.
Oil Cleaner.
A cylindrical type gauze filter is mounted between the oil canister
and the engine. The gauze elements are accessible from the rear
driving section by the removal of the top cap of the filter bowl. An
Auto Klean type filter operated by the clutch pedal is incorporated in
the same mounting.
Mounting.
The engine is mounted at four points on trunions in "Silenbloc" type
bushes. From the flywheel end the engine is inclined at 2deg from the
horizontal.
15. GEARBOX AND TRANSMISSION
Clutch and Gearbox.
From the engine the drive is transmitted via a dry plate clutch to a
crash type gearbox. This is integral with the clutch housing at the
engine end and mounted on a support fitted to each side of the chassis
frame at the other end. The mounting follows the same incline as the
engine, i.e. 2deg. The box contains two compartments. The larger
contains a five speed unit, fifth gear being direct. The main shaft is
mounted above the layshaft and the selector shafts are on the left
hand side. straight tooth spur gears are employed. In the smaller
compartment which is to the rear of the main box, next to the clutch,
is an overdrive gear. The gears are of helical tooth constant mesh
type. Fifth and sixth gears are only available to the forward driver
and it is necessary for him to depress a plunger type stop
incorporated in his change speed lever in order to pass the lever into
the gate for their selection.
It would appear that some difficulty has been experienced in engaging
third gear as the teeth on the pinions are badly burred. The change
speed levers are coupled by a shaft incorporating two cross pin type
universal joints and movement of the levers is somewhat heavy in
consequence.
A separate reverse gearbox is bolted to the output or forward end of
the main gear box and therefore reverses all the gears. Coupled
controls are provided to enable either driver to operate the reverse
gearing, the directional control levers being inscribed "INVERSORE."
"AVANTI - INDIETRO".
Distribution Box. (See Figs. 9 & 10)
The drive from the gearbox is transmitted via a short cardan shaft and
a large fabric disc joint to the distribution box. This box is mounted
approximately amidships in the chassis, and four separate output
shafts take the drive from the box to each wheel. In plan, therefore,
these shafts are in the form of an "X".
The drive into the distribution box is transmitted by a helical
toothed crown wheel and pinion to a differential unit. Each half shaft
from the differential drives through the helical bevels, one front and
one rear wheel. Thus the front wheel on one side is positively geared
to the rear wheel on the same side, and differential action can only
take place between the pair of wheels on one side and the pair of
wheels on the other. As four wheel steering is employed, the front and
rear wheels of each side move on a common turning circle and
differential action between them is therefore unnecessary. The
differential may be locked by means of a sliding dog clutch which
connects one half shaft with the differential casing. The four output
shafts pass obliquely through the chassis frame and each incorporates
a cross pin universal joint at each end. Each shaft is open after
passing through the chassis frame but is enclosed between the
distribution box and the frame, in two short tubular housings coupled
by a fabric gaiter which allow for the movement of the shaft. The
shafts to the forward wheels are 6" longer than those to the rear wheels.
Hub Reduction Gear. (See Fig.10)
The drive to each wheel is by separate helical toothed crown wheel and
pinion in the wheel hub, housed in a cast bevel box which forms the
brake back plate and supports the wheel bearings. The driving shaft
passes through the king pin axis - at a point where it incorporates
the outer universal joint - before entering the bevel box. The final
reduction gears are therefore unsprung
16. STEERING
Turning Circle - 41 ft. (To outside tyres in both forward and reverse
on either lock).
The steering of the vehicle is operated on all the road wheels
simultaneously from either the front or rear driving seats. This is
achieved by the coupling of the front and rear steering units by a
shaft incorporating two metal disc type universal joints. Actuation is
through bevel gears at the base of each column. The forward steering
column is mounted 6" to the near-side of the centre line and is
inclined towards the rear of the vehicle at an angle of 10deg. The
wheel is mounted at right angles to the column. Its movement is
transmitted through bevel gears at the top and bottom of the column,
to the coupling shaft and to a central worm and worm wheel. An arm
moving in a horizontal plane and integral with the worm wheel operates
rods which connect to a steering arm on each stub axle.
The rear steering column is mounted on the near side of the vehicle
and is inclined at 8deg to the offside to allow room for the driver's
right leg. The steering wheel is mounted vertically. The gearing is
similar to that used in the forward steering unit but longer shafts
are necessary to convey the movement from the column to the worm.
Owing to the large number of bevel gears used in the layout, there is
a considerable amount of backlash. A free movement of the steering
wheel of approximately 90deg to 100deg is possible.
Lubrication of the steering units is effected by remote Tecalemit type
grease nipples in the forward and rear driving sections. The word
"GUIDA" (Steering) alongside the nipples indicates their purpose.
17. WHEELS AND TYRES
The vehicle has four road wheels of detachable rim type and two spare
rims mounted on rotating carriers at each side of the hull.
Road Wheels.
The road wheels are of cast disc type of 1' l0" diameter (less rim and
tyre). Six spoke-like ribs are incorporated in the design to give the
necessary stiffness at the points where the securing clamps for the
detachable rims are fitted.
The wheels are bolted to the brake drums by six hexagon headed bolts
and the assembly is fitted to the hub with a key and secured by a
large hexagon nut. The hubs are mounted on ball races which are
lubricated from the final drive units.
Pressed hub caps are secured by six hexagon head set screws.
Spare Rim Carriers and/or Auxiliary Load Carriers.
The spare rim carriers consist of plain pressed discs. They are
mounted on cast hubs with a parallel bore forming the bearing on which
the wheel can rotate. The stub axles are bolted to the recessed hull
plate. The stub axle is mounted at a height which permits the tyres to
project 3" below the hull , this enabling the tyres to take the weight
when crossing rough country, thereby minimising the danger of
bellying. There is no drive to the spare wheels and there is no
reinforcement of the hull where the axles are attached.
Tyres.
Make : Pirelli Size : 9.74 - 24.
The tyres on the vehicle are of two types, four have a shallow sand
tread and are marked "LIBIA" whilst two have an orthodox deeply
moulded tread of the "Heavy Duty?' type.
18. BRAKING
Type: Lockheed Hydraulic
The main brakes on the vehicle are hydraulically operated on the tour
road wheels. They are applied by foot pedal in each driving section.
The reservoir is mounted on the nearside of the forward driving section.
The handbrake levers for each driver operate a transmission brake of
orthodox pattern, interposed on the cardan shaft between the gearbox
and the distribution box. The forward lever operates the brake via a
cable and the rear operation is by rod. FIG. 12
19. SUSPENSION
Type: Independent
Spring: Coil.
The wheel assembly is pivoted to the chassis on two wishbone type
radius arms. The lower radius arm is longer than the upper arm and is
attached to the lower end of the coil spring; the upper end of the
coil spring being attached by a bracket to the chassis.
Two hydraulic shock absorbers are attached to the upper radius arm at
the point where it is pivoted to the chassis.
The wheel ends of the upper and lower radius arms carry on trunnions
the king pins, one being above and the other below the universal joint
of the final drive shaft.
Some protection is afforded to the springs by 6 mm. plates turned
outwards at each end and bolted to the hull side plates where they are
cut away to accommodate the suspension units.
20. INSTRUMENTS AND CONTROLS
Front Driver's Controls. (See Fig.15)
The forward driver's foot controls consist of a clutch pedal on the
driver's left, footbrake in the centre and accelerator on the right. A
hand brake lever, change speed lever, and directional control lever
are situated on the right of the driver's seat approximately in line.
Hand controls for throttle, choke, and for advancing or retarding
ignition are mounted in a quadrant frame to the right of the gear lever.
Front Driver's Instruments. (See Fig.15)
There is a switchbox incorporating the following switches and
instruments mounted under the glacis plate to the right of the driver:-
Speedometer -Calibrated in kph from 10 - 100 (the figures in brackets
denote approximate speeds in mph)
1st. - 10 (6.2)
2nd. - 11.5 (7.2)
3rd. - 21.5 (13.4)
4th. - 38.5 (24)
5th. - 58 (36)
6th. - 78.5 (49)
Petrol Gauge -Electric type operated by float and rheostat mounted on
top of main petrol tank. The gauge registers fuel in forward and main
tanks only.
Ignition Switch - Cylinder look pattern incorporating pilot light.
Main Lighting Switch - Rotary type with three contacts.
Starter Switch - Push button type.
Panel Lamp - there is a bayonet type panel lamp holder with switch
incorporated.
Horn Button - mounted on steering column and operating orthodox
electric motor horn fitted on glacis plate
Rear Driver's Controls.
The rear driver's foot controls consist of a clutch pedal on the
driver's left, footbrake in the centre and accelerator on the right.
The hand levers are mounted on the left of the driver and comprise of
a handbrake lever and change speed lever on the left of the gearbox,
and directional control lever of crank type mounted on top of reverse
box and operating on a vertical axis.
Rear Driver's Instruments. (See Fig.16)
The electrical switch box is mounted to the left of the driver and
accommodates the following gauges and switches:
Oil Pressure Gauge - Graduated 0 - 50 in divisions of S Km/cm2. The
graduations 15 - 35 are marked in RED.
Water Temperature Gauge - Graduated 30o - 110o (with the graduations
95 - 110 marked in RED)
Ignition Switch- Of cylinder lock pattern. The key is deficient and
the key to the forward switch is not interchangeable.
Panel Lamp Bayonet type fitting with switch incorporated.
Main Lighting Switch - Of rotary type with three contacts, operating
lamps on rear wings.
Horn Button. - Mounted on steering column and operating large rotary
siren on engine cover plate.
21. DRIVER'S SEATS
The forward driver's seat is of adjustable sliding type. The backrest
is hinged to the nearside and secured by a barrel bolt on the offside.
It is necessary for the driver to swing the backrest open to enable
him to take position in his seat. The seat for the rear driver also
has a sliding adjustment for leg length. The backrest is hinged but is
easily removable. In order to take his position in the driving seat it
is necessary for the rear driver to remove his steering wheel and a
quick release in the form of a captive wing nut is provided for this
purpose.
22. COMMUNICATION
The mounting for the wireless aerial is situated forward on the
offside upper hull plate. The mast which is of 1" diameter aluminium
tube and 7 feet long may be raised or lowered manually by a handwheel
operating through bevel gears in a box mounted inside the roof of the
hull to the right of and slightly behind the front driver's seat. The
aerial is balanced in a vertical position by a counterweight and is
dipped automatically by contact with the 2 cm. gun barrel when it is
necessary for the gun to pass. The aerial may be held in the lowered
position by the handwheel which incorporates a spring loaded plunger
engaging in a hole in the bevel casing. The drive from the handwheel
to the aerial is not positive and the aerial may be raised or lowered
without damage should the handwheel be in a locked position. This
drive is in the form of an annular cam attached to the aerial pivot
shaft and driven by spring loaded followers attached to the bevel shaft.
The wireless sets are deficient but three flexibly mounted bases to
the front right of the fighting compartment would indicate that the
wireless equipment consists of a receiver, a transmitter and a power
unit. The wireless batteries are carried in a large container to the
left and right of the fighting compartment and are not charged by the
engine dynamo. They are deficient. The inter-communication system is
independent of the wireless. Supply for the inter- communication is
taken from the wireless batteries to a small rotary power unit mounted
to the right rear of the fighting compartment. This unit supplies the
high tension for a two valve amplifier mounted next to it. Four
control junction boxes are fitted in the vehicle, one for each driver,
one to the rear right and one to the front left of the fighting
compartment. These boxes have a red and green light, a three-way
switch ("Off", inter-communication, R.T), a socket for the throat
microphone (and presumably a head set5 jack and volume control. A call
button is also fitted to each box. Since a green light is fitted in
the lid of the amplifier the lights in the control junction boxes are
possibly to indicate whether the switch is to R.T. or
inter-communication.
23. LIGHTING SYSTEM
The vehicle is fitted with two head lights at the front, and two head
lights and a combined stop, tail and number plate light at the rear.
The lights are controlled from switches on the driver's panels as
detailed in para. 20.
The head lamps incorporate the side lamps having a side lamp bulb in a
lampholder behind the reflector which has a small talc covered window
cut in it near the centre.
The headlamps are fitted with double filament bulbs giving bright and
dipped illumination. To prevent the bulbs being inserted wrongly the
lamp holder bayonet catch slots are of different sizes as are the bulb
cap lugs.
The light switches have four positions, "off", "side," "dipped" and
"bright." Internal illumination is limited to three hooded lamps, one
on each driver's panel and one under the turret ring at the 12 o'clock
position. There are no circuits in the turret and no base junction is
fitted.
24. VENTILATION
In each forward side of the turret is an opening for ventilation
measuring 1.5" x 11.5". A B.P. cowl of 8 mm. thickness is bolted to
the turret side to protect each opening.
There is a further opening for ventilation in the offside hull plate
behind the spare rim carrier. This opening is provided with B.P.
protection in addition to that provided by the spare rim carrier.
The air taken by this inlet is directed through a metal duct to the
space between the fighting compartment floor and the belly trays at a
point slightly forward of the distribution box.
25. OUTSIDE STOWAGE
Mountings are provided on each side of the rear engine cover plate to
accommodate spades. One of the spades is deficient.
On the lower hull plate forward of the spare rim recess are two
brackets which form a mounting for a machete.
26. TOWING HOOKS
Robust towing hooks are provided and are riveted to the hull side
plates at the rear of the vehicle and to the upper nose plate at the
front.
A towing link is bolted centrally on the tail plate the link being
secured to the mounting by a clevis pin with a forked end in which is
a hinged retaining key.
A spherical attachment for a towing bar is mounted centrally on the
upper nose plates between the towing hooks.
A central towing eye is riveted to the lower nose plate. Lifting hooks
are not fitted to either the hull or the turret.
27. INSIDE STOWAGE
A wooden box to accommodate driver's episcope is mounted on the floor
of the hull on the left of the driver's seat.
A wooden shelf fitted to the turret flange on the left of the gun
forms stowage for the gun clearing tools.
A further wooden shelf on the offside of the turret flange is probably
intended to hold charger plates containing empty cases. Stowage for
spare M.G. barrels is provided by metal clips and leather straps on
the front of the wireless battery boxes.
On either side of the hull door openings are metal stowage bins which
are constructed to fit the radius of the spare rim and rear wheel
arches. The capacity of each of the rear bins is approximately 2 cu.
ft. and of each of the forward bins approximately 0.4 cu. ft.
Small wooden boxes mounted over each of the latter have a capacity of
approximately 0.3 cu. ft. and may be used to stow field rations. For
stowage of ammunition see "Ammunition Carried" Para 9.
28. FIRE FIGHTING APPLIANCES
There are mountings for two fire extinguishers on each side of the
fighting compartment. The mountings are a few inches forward of the
door openings and the extinguishers may be reached from outside the
vehicle when the top half of the doors are open.
Two of the extinguishers are deficient.
29. VULNERABLE POINTS
There are numerous chinks at the joints between plate edges,
particularly at the junction of the nose and hull side plates, and the
tail plates and side plates. In the case of the former the driver is
exposed to splash as is also the forward petrol tank. The gaps at the
rear, and the air intakes and outlets in the engine compartment,
render the radiators and engine liable to damage from the same source.
In fact absence of splash protection is general throughout the
construction, the gun mantlets, hull doors and vision and revolver
ports all being vulnerable.
Owing to the spring loaded bosses used in the hull door latches it is
possible for them to be forced open approximately 5/16". The crew,
particularly the hull gunner, and the rear driver, are thus liable to
suffer from S.A.A. attack directed at these points from the rear.
The commander's periscope is vulnerable since the object prism is
unprotected . This should constitute an important target there being
no other vision device s in the turret apart from the sighting
telescope and revolver ports.
30. RECOGNITION POINTS
The most striking feature in the vehicle's broadside silhouette is its
back to front appearance. This is accentuated by the deflector on the
hull top plates and the rear hull M.G.
From the front the large inset headlamps in the front vertical plate
with their B.P. flaps and the stove pile appearance of the 2 cm. gun
barrel are noticeable points. From the rear the long sloping engine
cover plate and ball mounted M.G. on the offside should afford
recognition points.
31. MANUFACTURERS MARKINGS
Chassis. No. 40788 MATRICOLA No. 40788
Armament.
2 cm. BREDA-CANONE DA 20 M/M CONTROAEREO - MOD. 1935 No. 3809 BRESCIA.
1910 - XVIII.
8 mm (Turret) BREDA 8 M/M METRAGLIATRICE MOD. 38 No. 157. 30 XVII
8 mm (Hull) BREDA METRAGEL TIPO C.A. CAL 8. No.2458 - 41 - XIX
Optical Instruments.
Turret Telescope. CANNOCCHIALE DI PUNTAMENTO SAN GEORGIO S.I.A. No.
88215. GENOVA SESTRI
Hull Telescope. No. 100293. GENOVA SESTRI
Periscope* CANNOCCHIALE PANORAMICO DI OBSERVAZIONE No. 94951 GENOVA
SESTRI
Engine.
(Engine Number) S.P.A. 518931 21-11-40 Abm.1 100041.
Petrol Pump. COSTR. ARRONAUTICHE FONDERIE SOMIA LOMBARDO ITALIA.
SECONDA ROTA AUTO FLUX.
BREVETTATO.
Magneto. MARELLI
Dynamo. MAGNETTI MARELLI D.90 RK. 1/12 ? 1100, 136495.
Accumulators. VARALLI.
Gearbox.
S.P.A 100039
Wheels.
GIANETTI IRRONNO.
Tyres.
PIRELLI SUPERFLEX 9.74 x 24.
Four marked- LIBIA. 1- T RAIFIX Nos: 133 A 361;101 C 930 E; MADE IN
ITALY. F.142 E 782; 642 H 351.
Two marked- HEAVY DUTY. RINFORZATO Nos. 640 C 914 E.L.; INPORTE
D'ITALIE 635 D 112 E.
Brake Reservoir
FIAT. FREUD-IDRAULICO SISTEMA. AUTOMOTIVE PRODUCTS C0. LOCKHEED
LICENZO. LONDON
Inter-Communication.
REGIA AERONAUTICA. INTERFONICO TIP. RA 42 INDUSTRIA RADIOTEONICA
Power unit No. 0156 ITALIANA Amplifier No. 0157 VIA ALBENGA No. 12 Roma
Fire Extinguishers.
ESTENTORE A TETRA 1/2 LITRE TELLUM. BREVETTI FERRA 2 CORSO MD. AZEGUO
72 TORINO.
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