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Type X Driving Impressions

The 1918 Type X lorry displayed at the Milestones Living History Museum was bought new after WW1 by a fruit farmer, selling damsons for jam making. He made enough profit during the first season to pay for the lorry, working day and night delivering damsons to the jam factory. During the ’sixties, the lorry came into the ownership of a farmer in Tenbury Wells, Worcestershire, who was looking for an old vehicle, and when he traced its history he discovered that the original owner had been the farmer next door to him, 50 years earlier! The ‘new’ owner restored the lorry and kept it running for years, and he is believed to have taken it to fêtes and other events.

 

Displayed at Milestones, this 1919 Type X is the subject of this page. Photo: Nick Corrie

The Thornycroft's owner was in his eighties when he offered it for sale to the HMAS. He was a great enthusiast, and was very sad to see the Thornycroft go, but after having had a stroke, he could no longer swing the starting handle. He decided that the X should go to a museum for permanent safekeeping. The vehicle was in running order when the HMAS received it, and its serviceable paintwork gave it the robust, comfortable appearance of a lorry in regular use. Therefore, the HMAS decided that there were no grounds for a costly, time-consuming repaint to coachbuilders' standards and, accordingly, the Thornycroft remained in as-found condition. In the event, very little refurbishment of any description was needed when the lorry arrived.

Bodywork 

The X has a plain load platform and a timber cab, the side and back windows and 'windscreen' of which are apertures devoid of glazing, as was normal in the Thornycroft's day. The cab roof extends forward to provide some extra weather protection, and the cab is reminiscent of that of a contemporary steam locomotive. There are no doors, but entry apertures either side of the cab may be closed off with canvas, rising from the bottom of the cab to just below the level of the steering wheel. The maroon paint job was hand-brushed by the previous owner, who evidently had a penchant for the colour as it appears that he used it on his farm sheds and vehicles, as well as his collection of stationary steam engines (from ships and factories)! As a farmer, the X's previous owner was possibly not an expert coachbuilder, but the results of his handiwork are very pleasing.

The cab is high off the ground and one climbs up to enter it, whereupon the cab provides a lofty perch for its occupants who sit on a wooden bench seat; the floorboards are made of wood. The parallel-sided bonnet - the Thornycroft's noble prow - stretches forward several feet below the occupants and gives a delightful vintage feel, with added effect from the external radiator topped by a filler cap, the separate mudguards and brass acetylene headlamps. The cab's lofty external appearance belies the very low roof seen from within, but this, and the roof's forward projecting hood help to keep rain at bay. The 20 gallon (90.9 litres) petrol tank is mounted on the dash, stretching from one side to the other, and, interestingly, is of riveted construction. The tank increases the value of the dash as a weather screen.

The driving position has the normal pedals, i.e. clutch, brake and accelerator, but the latter lies between clutch and brake pedals. Letters C and B are marked on clutch and brake pedals, respectively, possibly because fewer people knew how to drive during the Thornycroft's time. Gear-change and side-brake levers are mounted to the driver's right. The Thornycroft has two throttles, the foot throttle (i.e. accelerator pedal) already mentioned and a hand throttle, the latter being mounted on the steering column. A manual ignition advance-retard lever is also on the steering column, just below the hand throttle.

Engine 

The Type X's M/4 engine is a big 6.26 litre petrol-driven 'four' developing a leisurely 40bhp. The type was originally designed as a marine engine, but, rather than design a new automotive engine for its lorries, Thornycroft simply fitted the proven M/4. It is a T-headed cross-flow engine with inlet valves on one side and exhaust valves on the other. There is no electric starter, and the engine is hand-started with a handle projecting in front of the vehicle. Such a large engine has a lot of metal to turn manually, but the M/4 starts easily once the knack of bringing it to life is mastered. The ignition must be retarded for starting, and failure to give enough retard can make the engine kick back with enough force to injure the person on the starting handle.

Engines needed much more maintenance in 1918 than they do now. For instance, ignition contact-breaker points routinely needed setting and replacing, and tappets needed setting. Build-ups of carbon had to be removed from inside the engine due to the lower quality of early petrol. Frequently, valves had to be reground to maintain effective sealing. Indeed, the driver was expected to carry a spare valve or two and springs, and the engine design was such that the driver could change the valves by the roadside, through a screw cap above the valve. He might also have had to replace broken valve springs. Engines also needed major overhauls during their lives, although less frequently than the above lesser routine operations.

Transmission 

The Thornycroft Type X has a four-speed manual gearbox separate from, and shaft-driven by the engine; the clutch is in unit within the external flywheel. Drive goes to the back wheels by propeller shaft and Thornycroft's usual worm-driven differential. There is no synchromesh, and in its absence Thornycroft drivers had to change gear as follows, to overcome the problem of bringing spinning gearwheels into mesh when they are turning at dissimilar speeds:

Changing down: the driver double de-clutches, part of which involves spinning up the engine in neutral with the clutch engaged (see on the road), in order to match (as far as possible) the peripheral speeds of the driving and driven gearwheels within the gearbox to enable them to mesh.

Changing up: when the engine is disengaged from the clutch during a gear change, the momentum of the heavy gears and the gearbox side of the clutch keeps them spinning. A clutch stop is provided, a type of brake operated by the clutch pedal (see on the road) designed to slow down the gearbox side of the clutch, enabling the driving and driven gearwheels to mesh.

Brakes
The Type X has unassisted rod-operated brakes, having been designed in a generally pre-hydraulic brake age. Brakes are fitted to the rear wheels only, and there is a transmission brake. The sidebrake lever to the driver's right is the main stopping brake for use on the move and operates the rear brakes. It also serves as a parking brake and is fitted with a ratchet. The pedal-operated transmission brake is normally for emergency stops only. The Thornycroft is driven with a degree of anticipation in deference to the braking system, but at 20mph (32kph) events take a long time to happen!

Lighting

The X has acetylene lights, which function by burning acetylene gas produced by reacting calcium carbide with water. They give out a bright white light, and are said to be very effective.

Horn

The horn is a hand-operated mechanical device mounted on the cab side to the driver's right. It is a marine horn and is quite strident, deriving its note from a small internal ratchet. Most Thornycrofts had a horn like this, or a bulb horn.

On the road 

The Type X's top speed is about 25mph (40kph), although around 20mph (32kph) would not normally be exceeded, corresponding to 1,250rpm. At one time Thornycroft lorries were governed to 12mph (19.3kph), but during WW1 drivers used to disconnect the governors to give more performance! With only rear-wheel brakes and a transmission brake, the driver must plan more carefully nowadays than in 1919, when lower traffic densities were normal.

Certain features of motor vehicle design had not become standardised by 1919, when the Thornycroft was built. The gear lever operates through a gate type quadrant with the familiar H layout, but the gear change is back-to-front by modern standards and this can confuse a driver accustomed to the modern layout. Thus, first gear is back left, second is front left, third is back right and fourth is forward right. When changing up, the clutch pedal is depressed sufficiently far to 1) disengage the clutch and 2) to activate the clutch stop, and then the driver pauses briefly before changing gear (see transmission). Double de-clutching is necessary when changing down, and this is carried out by 1) depressing the clutch pedal, 2) moving the gear lever into neutral, 3) releasing the clutch pedal, 4) spinning up the engine, 5) depressing the clutch pedal again, 6) selecting the next, lower, gear, and 7) releasing the clutch pedal! Not surprisingly, this procedure needs skill when the driver is trying to concentrate on other driving matters, and if the process is not carried out properly it is impossible to change gear! All this slow-moving vintage machinery makes gear changing a leisurely process, and it takes a little time to spin up the engine.

The hand throttle on the steering column is akin to a modern cruise control, and the knurled quadrant preserves the chosen throttle setting. Except for starting (when retarded ignition is required for safety reasons) there is no fixed setting for the ignition advance-retard lever. The ignition timing required depends upon engine speed and throttle demand, and the driver adjusts the ignition timing to give best results. However, the previous owner of Milestones' Type X decided that he wanted the advance-retard and hand throttle levers to operate in unison, so he clamped them together! Thus, when the vehicle is started a small throttle opening is selected, and this will select a retarded ignition timing required for starting. Once on the move, opening the throttle advances the ignition timing. This private mod would, of course, prevent the driver from adjusting the ignition timing independently, a freedom of adjustment that might be desirable under certain driving conditions.

The X is surprisingly agile and is much easier to steer than might be imagined, but traction on wet grass is poor. It needs to be treated with respect and should not, for instance, be driven over cat's eyes or kerb edges. The gearing allows the Thornycroft to slog up surprisingly steep hills.

Thornycroft instructions to drivers 

These were posted in the cabs of the J and X lorries, and are reproduced verbatim. Metric equivalents are absent from the original and have been added below.

Instructions To Drivers

For Running Thornycroft Types "J" And "X" Vehicles.

Before Starting Engine

Fill up Radiator.

Fill up Petrol Tank.

See that the gear-box has sufficient oil, charge all greasers on chassis, and screw right home to prevent loss.

Lubricate all brake-rod joints, clutch bridle, and other working parts.

Starting

If engine is stiff to turn when cold, ease with a few drops of paraffin through compression cocks.

To start engine, nearly close throttle, advance spark about halfway, switch "on" and flood carburetter (sic).

Open throttle very slowly until engine is warmed up, or she will choke. When starting from "cold" if she stops after a few revolutions, try flooding carburetter (sic) and opening throttle gradually at same time.

When flooding carburettor, push float down gently; it is not necessary to bang it up and down - by doing this the float may be damaged.

Release Hand Brake Before Starting Vehicle.

Lubrication

Immediately on starting the engine, see that the oil gauge on dash shows 10/15lbs (0.70/1.1kg/cm2) pressure. If the action of the gauge is irregular, see amount of oil in crankcase is indicated by the float on the top of the crankcase. The mark on the spindle should be 1in (2.54cm) above bottom of guide. If full amount of oil is in the crankcase then prime pump by filling brass priming box on front of engine casing through the screw plug.

Changing Gear - "Up"

Press clutch pedal WELL down, and slightly pause between each speed before engaging gear,

Changing Gear - "Down"

Leave the throttle open, press clutch LIGHTLY and move gear lever into neutral position, letting in clutch at same time, press clutch again and push lever into position, thus making two movements with clutch pedal, always remembering NOT to push pedal hard down during changing down.

Speed Control

Always change down rather than slip the clutch when engine is labouring.

Pulling Up

Always stop gradually (except in case of sudden danger) by declutching, throttling and applying side brakes.

Chassis

Wherever possible, look round and tighten all bolts and nuts on chassis and body.

Valves

When these are correctly adjusted there should be sufficient clearance left so that a visiting card can be pushed between valve stem and tappet. Make sure each valve is right down on its seating before making any adjustment. 

If the valve sticks in its guide, take out and clean the stem. 

All Adjustments Should Be Made After The Engine Has Thoroughly Warmed Up.

Magneto

Oil magneto where marked "oil" once a week with a FEW drops.

Clutch

If the clutch is slipping, tighten up the two nuts on the studs which project from the face of the fly-wheel, taking care that they are tightened equally, otherwise the sliding member may cross-bind on the shaft.

Greasers will be found on the sliding member, and MUST be filled regularly.

If clutch is fierce, put a few drops of engine oil on the clutch face.

Gear Box 

Good quality oil should be used. Fill box up to centre of bottom shaft, so that all bottom wheels dip in oil. After about 400 miles (644km) running, see whether more is required.

Steering Gear

Joints MUST be kept properly adjusted and lubricated. Do not force front wheel round by steering wheel when vehicle is stationary; this is apt to strain steering gear.

Wheels

Fill up greasers often and screw caps on hard, so that these will not shake off.

Adjustment of Brakes

Foot brakes with a wing nut. Side brakes by right and left-hand threads on side brake rods, adjust both rods equally.

Back Axle

Level of oil must be kept up to top of filler cap at back of axle casing. Grease must NOT be used. 

Torque and thrust are taken by the SPRINGS in this chassis, therefore watch spring clips and tighten at once if slack.

John I. Thornycroft & Co. Limited, Basingstoke, England.

Acknowledgements 

Acknowledgments for providing driving impressions and information about the 1919 Type X lorry car are due to Mr Sean Wiles, Conservator of Industrial History, Hampshire Museums Service. Research and writing by Nick Corrie.