An Alligator
Page 33
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by Pitt
THREE hew semi' trailers are to be shown by Charles Pitt (Barton Stacey), Ltd., at the Commercial Motor Show. One is a conventional tandem-axle unit and the other two are designed to give lowloading facilities.
The name Alligator has been given to one of the low-loaders. This is a 12ton single-axle drop-frame unit and employs a unique method of obtaining a clear platform for groundlevel loading as on a knock-out axle semi-trailer. It has much the same scope as that type of unit but with a quicker action. Instead of the wheels having to be removed, they are lifted clear of the loading area.
This is done by mounting the axle and suspension in a fabricated structure comprising the side-boards and wheel boxes. This is the full length of the drop wells and is hinged at the end of the front raised section. The whole assembly is raised by hydraulic rams (safety ratchet assemblies 'are also fitted) at the forward end of the well and, when fully raised, there is 11 ft. of headroom under the wheels. Hydraulic controls are located at the nearside of the upper deck and power is provided by a hydraulic motor driven by a power take-off on the tractive unit. The lower deck of the semi-trailer measures 13 ft. 8 in. x 6 ft: 10 in, and the upper deck is 7 ft, 11 in. x 7 ft. 4 in. The all-welded frame is made from rolled-steel channel. with four main members and cross members. Suspension is by leaf springs and a Rubery Owen 20,000 series axle is used. Brake units are Crirling 15.5 in. x 6 in. wedge operated, powered by a two-line air pressure system.
The second low-loader is the L.35 5/6ton semi-trailer. This is a smaller capacity version of the L.15 ground
loading drop-frame semi-trailer introduced last year. (described ,in I IN, Commercial Motor, August 18, 1961). II has the same trailing-arm, independent rubber suspension .but in single-wheel formation. The rear of the dropped platform can be lowered to ground level hydraulically for loading purposes Hydraulic powerlor raising the deck by means of Adrolic rams is provided by a Lister S.L.I. engine coupled to a Plessey pump, The lower deck is 14 ft. 6 in long and the gap between the wheelboxes is 5 ft. 3 in.
Tandem-axle Model
The tandem-axle semi-trailer to he shown will have a flat platform 25 ft. long by .8 ft. wide. Unladen height at the rear is 4 ft. 4 in. Fitted with a 2-in.diameter S.A.E./S.M.M.,T. kingpin, the unit has been designed, to operate at a maximum gross train weight of 24 tons to give a nominal capacity of 16/17 tons. The frame side members are steel pressings swept up at the front. The deck is of half lapped hardwood board, laid transversely and a 2-ft.-high headboard is fitted.
Suspension is by leaf springs and the axles arc Rubery Owen with 15,5 in. x 6 in.. S-cam brakes. A two-line airpressure braking system is employed.