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Ingenuity in
Page 84
Page 87
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Trailer Design
By P. G. Tucker TRAILER makers can always be relied upon to meet the most unusual transport demands, as is fully borne out at each succeeding Commercial Motor Show. The present Exhibition is certainly no exception. An outstanding example of this nature is to be found in the Cranes 30-ton drilling rig (Stand 98) which was built to the order of the Oil Well Engineering Co., Ltd., for supply to the Iraq Petroleum Co., Ltd.
The weight of an oil-drilling rig may be anything up to 100 tons and it may cover an area of about 30 sq. ft. In the ordinary way, it is necessary to completely dismantle these rigs when they have to be moved from one site to another, and the object of the Cranes bogie is to remove that necessity.
The drilling rig must be provided with suitable scatings at three points. designed to take a bearing on the upper ends of the hydraulic rams, one of Which is fitted to each of the three bogies which it is necessary to employ. With the rig in position, the bogies are manceuvred until the ends of the rams fit into their seatings on the drilling rig.
When the rams are operated, which may be done manually or by power, the rig is lifted clear of the ground and is then free to be hauled to any point required. One bogie is mounted forward and two in line at the rear, to give a three-point suspension arrangement.
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Cranes is also showing a model of an eight-wheeled bogie made up of four pairs of wheels mounted on Z axles. These bogies are sent in pairs overseas, and the operator builds a body on them. The payload of a machine incorporating two of these bogies is 16 short tons. The object of the particular wheel arrangement adopted is to distribute the load in a way which is impossible with the normal type of four-in-line layout.
Taskers of Andover (1932), Ltd., has an entirely new 25-ton low-loading machinery carrier which has been designed for overseas use (Stand 85). It differs from normal vehicles of this kind in that it has a four-wheeled bogie
with each pair of wheels in line ahead. They are free to oscillate in a backward and forward direction about a substantial steel pivot.
The bogie is retained in the chassis in a semi-circular seating in the rear end of the frame and is prevented from moving from it by a substantial U-bolt, which, however, does not take any load. By running the nuts of the U-bolt back to fixed stops, the bolt can be pushed forward and pulled to one side, which leaves the axle free to be withdrawn by hand. Jacks are, of course, used to take the weight off the bogie during this operation.
The Taskers four-wheeled 6-ton tipping trailer has a self-contained tipping unit driven by a J.A.P. 3i h.p. four-stroke petrol engine. This unit is mounted in a housing formed on the left-hand side of the machine. The body has twin-ram tipping gear and airpressure braking on all wheels.
Oil-filter Carrier
Designed for the Eastern Electricity Board is a Multiwheeler 1-ton twowheeled trailer, of which the unladen weight is 15 cwt. It is to be used for carrying oil-filtering plant and in these duties will have to find access to the positions in which the Board's oil transformers happen to be erected.
This means that there are occasions when the whole plant has to be removed from the trailer. To provide for this, inbuilt jacks at the front raise the body until the floor lines up with the angle of the tailboard ramp.
Where the transformer is more accessible, the sides of the body can be opened up, the lower lortion forming a platform which the men can use to attend to the filtering p:ant. The object of filtering the transf )rmer oil is to remove the condensate which accumulates over a period. 1 he body of this trailer is in aluminiun alloy, and it runs on 23 by 5 twin tyres.
In the export version of the Hands 12-ton semi-trailer to le seen on Stand 90, one of the main c 'oss-members of
the frame is removable. The object at this is to leave a clear space in the frame for packing the various components, the only extras required to complete the " crate" being top and bottom boards.
On the Hands fifth wheel a safety catch is now fitted, so that the driver need never be in doubt whether the coupling pin is properly home and locked in the jaw. In the Hands oita bath turntable, as fitted to the 10-ton four-wheeled trailer, all loads, however imposed, are taken on an oil film, the result being that resistance to turning movement at this point is at a minimum.
With an unladen weight of 2-1 tons, the Dyson 15-ton semi-trailer on Stand 58 has body, wings, support-gear casing and brake drums in light alloy, the last named being steel lined. Much weight has been saved by liberal piercing of the main-frame side members, which are 15 ins. deep.
Drip-feed Lubrication
Lubrication of the bogie balancebeam pins is provided for by a dripfeed arrangement, the supply of oil, which is considered to last the life of the semi-trailer, ,being carried in a tubular cross-member ruining between the spring-rocker housings. The Girling brakes are fluid operated by Clayton Dcwandre air-pressure equipment.
Many types of Dyson trailer and semi-trailer are shown in the form of scale models, which are towed by appropriate tractive units round a track built into the platform body mounted on a 40-ton convertible semitrailer.
Just how small a space into which it is possible to pack a 10-ton semitrailer can be seen on Stand 100, where the British Trailer Co., Ltd., has one of its Dragon machines broken down and packed in a space measuring 20 ft. by 7 ft. 3 ins. by 2 ft. 7 ins.
This concern has given considerable thought to the packing-for-export problem, as is evidenced in the B.T.C. Airflow 11 50-Seat semi-trailer coach. This model was seen at the 1950 Exhibition, but the present example shows evidence of much tidying-up. It is built in 12 main sections, being designed so that the whole packs flat for export.
The B.T.C. Twinspring system of suspension, in which two semi-elliptic springs are used, one above the other, provides the equivalent in load carrying to a single spring having a large number of heavy leaves. In action, however, the dual-spring arrangement has operating characteristics which tend to provide a more comfortable ride than is obtained with the conventional suspension layout.
A notable semi-trailer exhibit on the Carrimore stand (97), is an 8-ton fully cranked model, on which is mounted a special body for carrying gowns. The length of the body on the top platform is 10 ft. I ins., whilst the length of the lower platform is 15 ft. 11 ins. At
the point where the frame of the semitrailer is cranked, a sliding door is fitted. The tail door is hinged at the top and bottom and when opened the lower portion forms a ramp and the top portion swings up to form a protective canopy.
This Carrimore chassis has the Quickfit coupling gear and the maker's Retractor turntable. An automaticcontact coupling valve connects the servo pipe-line and seals the vacuum pipe on the tractor unit when the vehicles are separated. Provision is also made so that the rear lamp, stoplight, direction indicators and internal lighting are automatically coupled up.
Various ideas are adopted to provide for the automatic release of the tailboard of tipping vehicles. Simplicity of design and robustness in construction are main essentials, and in the device shown on the Eagle 5-cubic-yd. endtipping body (Stand 35) these features are combined in a release gear which should scarcely fail if completely forgotten.
Automatic Release
The tailboard is hinged at the top and retained in position by three L-shaped catches mounted on a cross-shaft. Attached to the cross-shaft is a form .of bell-crank, which in its turn is linked to a bracket secured to a frame crossmember. The different relative movement of the body about its pivot pins as it is tipped, and that of the bellcrank, causes the catches to drop away and release the tailboard.
On the Eagle 25-ton low-loading semi trailer the leads running to the taillamps are carried through tubes secured to and conforming to the curvature of the wings.
Anticipating the new lighting regula tions for trailers, an Eagle 6-ton fourwheeled trailer for British Road Services has two large tail-lamps and two lamps on the foremost edge of the platform body to show a white beam forward.
So once again the trailer makers are showing that when there is a load to be carried, no matter how difficult the operating conditions, they can make a machine to do the work. It is particularly noticeable, too, that the standard of finish of all the trailers and semi-trailers exhibited is of a high order.