||6 cylinder in line
||S.P.A. 518931 21-11-40 Abm.1. 100041
(See Foreword) capacity not measured. Estimated maximum B.H.P. approximately 100 - 120.
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.
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.
Of up-draught type and mounted on off-side of engine under exhaust and inlet manifold.
The exhaust manifold is on the offside of the engine. A cylindrical silencer is mounted on the hull side.
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.
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.
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.
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.
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.
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.
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.
Water; radiators (sealed system), centrifugal pump and two fans.
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.
A centrifugal water pump is driven in line with the dynamo and governor.
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.
A large Lanchester type vibration damper is mounted behind the fan drive pulley.
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.
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.
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
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.
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.
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.
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
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:-
Rear Driver's Controls.
- Speedometer -Calibrated in kph from 10 - 100 (the figures in brackets denote approximate speeds in mph)
||- 10 (6.2)
||- 11.5 (7.2)
||- 21.5 (13.4)
||- 38.5 (24)
||- 58 (36)
||- 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
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.
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.