Raising Overturned and Ditched Buses
Page 35
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A Demonstration of the Metliods and Means Employed by Crosville Motor Services, Ltd.
OME time t• go there was a bus
mishap in which a double-deckel.
ov-rturned and obstructed a highway for a considerable time. In order to void delays. in incidents of this type, as well as where buses are ditched, the engineering department, of CrOsville Motor Services, Ltd., gave demonStrations of its methods at the company's Mold Road Garage, Wrexham, on August 1. The main object was to perform these operations by utilizing equipment which could be constructed by anyone possessing a small workshop.
The materials required are as follow:—One set of rope pulley blocks (threr and two sheaves) reaved With i-in. diameter steel-wire roe; two 7-ft. 6-in. by 4-in. by 3-in. H-section girders with suitable attachments at each end, and a distance tube to keep them apart while under stress; one snatch block; one 15-ft. length , cliainUer steel rope, shackled at each end; two 9-ft. lengths of 2-in, diameter, flexible steel rope to secure girders to chassis: two non-skid plates to form a cradle for the under wheels of the : overturned vehicle; 18 lengths of timber 4 ft. by 9 ins. by 4 Ms. (pit planks).
Say tha-t-a double-decker is lying on its side in a road 30 ft. wide. This is pulled on to its wheels by means of girders secured to the underside of the chassis frame, giving a_10-ft. leverage from the fulcrum point. A wire rope is attached to each end of the girders, and at approximately its. centre, the upper block of a set of pulley blocks is hitched, whilst the lower block is securely anchored to seine stationary object .12 ft. from the underside of the overturned vehicle (in the demonstra: titan a single-deck bus was used).
The loose end of the rope threaded through the pulley block is passed through the snatch block, which is secured adjacent to the lower block.The end of this rope is attached to a towing vehicle To prevent excessive shock when the vehicle is brought back on to its wheels, packs of timber, some 12 ins. to 15 ins, high, are built as landing stages-for the wheels.
Dealing sequentially with the operations:—The distance tube is first placed on the ground alongside the chassis, to define the points at which the girders are to be fixed. The girders are then placed in position, the distance tube moved to their upper ends. and this and the 15-ft. length of steel rope is secured to them by means of pins and shackles. The frame thus made is lifted and secured to the underside of the chassis by means of the Iwo 9,ft. wire ropes.. Next, the two non. skid plates are placed under the wheels to prevent, them from lipping. Finally, after the bus has been righted, the girders are removed and the vehicle towed backwards off the planks.
The minimum number of men essential for the operation is five, hut more can be used with advantage.
As regards a ditched bus, rescue can be successfully carried out with the aid of a pair of shear legs approximately 7 ft. in length with a U-shackle at the top and a shackle chain suitable for bolting on to the wheel studs, making use of rope blocks as a lifting medium. In the operations, first a -piece of II-section girdle is placed .alongsidt the ditch in a suitable position to obtain a foothold. On this is laid a plank (4 ft. by 9 ins. by 4 ins.) to form a base for the shear legs A snatch block is suspended from the top of these, and a length of rope secured at: one end to the front-wheel studs and the other to the top of the shear legs. • The lastnamed forms an anchorage (or a pull in the direction of the rear wheels. One end of a wire rope is secured to the 'studs of a rear wheel, thence through a system of pulley blocks until the othet end is fastened to a towing vehicle
As the toWing commences, the lower rear wheel of the ditched vehicle 'is lifted out sufficiently high to enable bridging planks to be placed unde.• it. The wheel is then lowered on to these and the pulley blocks remoVed. The bottom block is now secured to a suitable anchorage and the upper block to a rear spring of the vehicle, the Loose end. of the fope being passed through a snatch block near the bottom block:
On towing, the rear of the ditched bus slides sideways on to the road; being assisted, particularly in the case of waterlogged ground, by skid plates under 'the wheels which are .heilig pulled sideways. After rearranging the pulley blocks, the vehicle earl be towed backwards clear of the ditch.