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with Exceptionally Low Platform
A Carrimore Eight-wheeler, Built for 25-ton Loads, with a Loading Height of only 2 ft. 6 ins. Ingenious Construction Employed to Keep within this Dimension AANY points of interest are to be found in a large 11(kt-railer that has just been built by Carrimore Six Wheelers, Ltd., North Fincbley, London, N.12, for the South African Railways and Harbour Board, to the order of the Griffin Engineering Co., Ltd., Johannesburg. An eight-wheeler, it has a carrying capacity of 25 tons, whilst the platform, which affords an unbroken surface of 1,650 sq. ft., has a height when laden of only 2 ft. 6 ins.
In view of the fact that the wheels are shod with 20 by 6 solid tyres (of which there are 16 in all) and that the main frame members are 7 ins, deep, it is clear that no space has been wasted. Without load, there are only 3 ins, between the tops of the wheels and the underside of the frame. The complete trailer weighs 4 tons 6 cwt.. and has been designed for a maximum speed of 8 m.p.h.
At the front there are four wheels arranged in line, these being mounted in pairs on two rocking axles, whilst at the rear the wheels are arranged in tandem on two full-length axles. Woodhead trunnion-ended springs are employed for the front suspension, and an interesting point in their design is that provision is made for longitudinal movement of the rear ends without the employment of shackles.
Height-saving Platform Construction.
Measuring 22 ft. by 7 ft. 6 ins., the platform is floored with 14-in. oak and surrounded by a rectangular frame of 7-in. channel, The structure also embodies two .inner longitudinal members, which connect the two end crosschannels and are built in the same plane, so that their top faces are flush with the floor surface.
Each of these inner members is formed, for about a third of iis, length from the front, of two channels placed together back to back. For the remaining distance, two channels are spaced apart, the forward and rearward pairs overlapping at their join.
Between the spaced members, the rear-spring balance beams operate, whilst on their lower faces are fixed the rear spring brackets and the pivots ,carrying the beams. The last-named are coupled to the adjacent ends of the springs by short links, in the usual manner.
A rectangle of lighter channel comprises the front undercarriage, and to this are attached, on the lower side, the spring trunnions and on the upper side the turntable • ring. It also incorporates the king-pin mechanism and the drawbar brackets. Amidships four 5-in., channels run the full width of the taller and are riveted to the under faces of the longitudinals. Upon them are wooden pieces, supporting the floor. For this purpose there are also two light crossmembers over the bogie and two more over the front axle; the latter carry the upper turntable ring. To take the floorboards at the ends, two lengths of angle-section steel are fixed to the inner faces of the large crosschannels.
Brake drums, 16 ins, in diameter and 3 ins, wide, are mounted on the four rear wheels. They are operated from a cross-shaft through compensating levers, application being effected from the tractor or from a screw-handle at the off side. For the former, a cable runs through a tube and emerges through a hole in the front channel, whilst for the latter a separate cable runs around a pulley to a nut on the hand-screw. It is claimed that the brake will hold the trailer with full load on a gradient of 1 in 5. Solid square-section steel is used for the straight rear axles, and all wheels run on tapered-roller bearings.
Novel Front-springing Arrangements.
The method of dispensing with shackles for the front springs is ingenious and quite Simple. In one of the accompanying pictures the trunnion end can be seen, and it will be noted that the bulk of the weight is taken by the cylindrical trunnion block, which bears on the second spring leaf. There is a generous clearance (at the back ends of the front springs) at. each end of this block, so that sufficient end play is permitted to obviate the need for shackles.
In point of fact, the trunnion member is cross shaped, the cylindrical portion, the axis of which is parallel with the line of the spring, being extended forwards and rearwards. These extensions pass, in the one case, through a hole in the bent-up second plate and, in the other, through the solid eye of the top plate, which also carries a clip
embracing a number of other leaves. It is, of course, important that there should be provision for end, play at only one end.
Jonas Woodhead and Sons, Ltd„ Leeds, we are informed, made these springs, which are a modification of a standard design, expressly to ineet the requirements of this trailer.
We understand that this interesting Carrimore product will be used chiefly for carrying machinery and similar goods, and that its field of operation will be limited to docks, etc., where it will not be called upon to leave hard, smooth-surfaced ground.