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A 6 x 6 Land-Rover Outfit
Page 156
Page 157
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ONE of the interesting novelties tucked away among the gallery exhibits at the Earls Court Commercial Motor Show last September was the Bushmaster powered two-wheeled trailer shown by Scottorn Ltd., of New Malden, Surrey, and intended for use behind LandRover vehicles. This trailer is based on an idea given to Scottorn's by the Rover Co. Ltd. in an attempt to develop a six-wheel-drive cross-country unit. Extensive testing under arduous conditions has shown the design to have decided possibilities, and this I was able to prove for myself recently when I subjected the Land-RoverBushmaster combination to a morning's work over the F.V.R.D.E. rough tracks at Bagshot Heath.
The use of the Bushmaster trailer (the name, incidentally, is that of a South American snake with the ability to cover rough ground at high speed) increases the already admirable cross-country abilities of a basic Land-Rover-trailer cornbination and makes it possible to carry a payload of 1.5 tons and at the same time negotiate particularly soft terrain and generally overcome various difficulties which normally would be near impossible for an ordinary Land-Rover and trailer. The outfit .tried out at Bagstiot Heath consisted of an unladen Land-Rover and a laden Bushmaster weighing 1.6 tons, and the value of the additional traction provided by the driven axle of the trailer was shown on numerous occasions when muddy and loose-surfaced slopes of at least 1-in-3 (33-3 per cent) severity were tackled: on such gradients the combination could be brought to a standstill without the trailer drive engaged, after which entirely successful restarts were made once the trailer axle was called upon to play its part As further proof of the value of the Bushmaster's traction, several times the Land-Rover was driven part-way down slopes of 1-in-2 severity (50 per cent) and then, by engaging the trailer drive only, the complete outfit was hauled back up the slope. The arrangement of the gearing is such that the combination can be used as a 6 x 2, a 6 x 4 or a 6 x 6, engagement of the trailer drive being quite independent of that of the Land-Rover's axles. Another feature is that 'the trailer drive can be used when high ratio of the Land-Rover's auxiliary gearbox is in use, thereby giving six-wheel drive at speeds of well over 50 m.p.h.: this attribute is of particular value when travelling over soft sand, under which conditions a surface speed of at least 35 m.p.h. and drive on all wheels is desirable.
The Bushmaster trailer is similar to the standard Scottorn 1-5-ton/250-gal. design, differing principally in respect of axle and suspension. The axle is the 'standard unit from a 109-in.-wheelbase Land-Rover, this having been chosen particularly because of its II in. by 2.25 in. brakes. Free-wheel manually operated hubs, as made by Mayflower Automotive Products Ltd., Plymouth, and marketed by Rover's for front axles, are fitted to the axle to prevent the drive shaft between the towing and trailed units turning when the drive is not required: these hubs have to be locked-in when trailer-wheel traction is needed as the free-wheel effect takes place in both directions of rotation, but fortunately the locking bolts (one per hub) are the same size as the wheel nuts, so the wheelbracc can be used for this operation.
Suspension Under Development The brakes are actuated on the over-run system, incorporating the latest Scottorn design. The suspension is still under development, but in final form can be expected to consist of Land-Rover single-rate front springs plus Aeon rubber helper springs plus variable-rate dampers. The power input to the axle is taken from an input point on the front of the trailer frame, this being carried in a robust bearing assembly: the link between this and the axle is a standard short-wheelbase Land-Rover propeller shaft with Hardy Spicer joints.
Drive between the Land-Rover and the Bushmaster is taken by a wide-angle agricultural-type shaft, longitudinal movement being accommodated by a square sliding joint. This shaft is quickly detachable, being held on the splined output and input shafts by spring-loaded pins. A normal Lind-Rover heavy-duty towing hitch is employed for the drawbar connection. A normal Land-Rover power take-off is used for the trailer-axle drive the line between the power take-off and the output point passing through a secondary transfer box which is the same as the auxiliary box attached to the main gearbox except that it is used back to front, thereby correcting the direction of rotation and shaft speed. The secondary box is at the rear of the Land-Rover and its location entails a box 19 in. long, 14 in. wide and 6 in. high mounted on the Land-Rover floor.
The trailer-axle drive is engaged by pulling out the power take-off knob, whilst the speed-change lever for the trailerdrive box is interlinked with the high/low-lever of the standard auxiliary box to avoid the possibility of low ratio being engaged for the Land-Rover with " high " in use on the trailer, or vice versa.
It will be seen from the above very brief description of
the Land-Rover-Bushmaster combination that the maximum use has been made of standard Land-Rover components where additional equipment is required, and this will be a big attraction to operators in isolated areas who are already assured of good Land-Rover service facilities. It also helps to keep the price down, provisional figures being £320 for the driven trailer chassis and £130 for the conversion of the Land-Rover. J.F.M.