A 25-30-ton Attachment with new features
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I NCORPORATING a number of valuable features, a new design of machinery-carrying semi-trailer attachment for 25-30-ton loads has recently been delivered to J.. R. Carrnichael•and -Co., Ltd., Edinburgh, by the maker, R. A. Dyson and 'Co., Ltd., 76-80, Grafton Street, Liverpool, S. Of sturdy construction, the frame is tapered, having a width of 7 ft. at the front and 8 ft. at the rear. This arrangement gives the advantages of a wide track and estilts in good stability at the rear, whilst, it is claimed that the narrower front end improves the manceuvrability of the outfit. • The dropped section of the frame is inclined so that the ground clearance at the front is 13 ins., whilst at the rear it is only •ti ins. The reason for this is two-fold; in the first place no springs are provided at the rear of the trailer so that allowance must be made for the deflection ol the springs on the tractor unit. Secondly, due to the length of the semi-trailer (33 ft. 2 ins.), the possibility arises of the frame •grounding on hump-backed bridges ; the inclined frame minimizes this risk.
To permit of -end-loaaing, each of the rear bogies is constructed so that it is easily detachable. Reference to the accompanying drawing will show that each bogie rocks about a tubular shaft, the spindle of which can be easily removed. Three jack platforms are provided, one being permanently in position in the centre of the frame at the rear, whilst the other two comprise removable clips which fit on the outside of the chassis.
Hinged Ramps to Facilitate EncWoading.
Loading ramps of unusual design are a feature of the outfit, and these comprise two sections hinged to the rear end of the frame; they are cut away to clear the wheels. When not required they are held in a vertical position by means of stays.
The procedure when end-loading is required is as follows.:—First, the jacks are placed under the platform provided, and the load taken on them ; the spindles in the tubular centre shafts are thenremoved—the bearings rei»aining in position—andthe bogies wheeled clear; the frame is then lowered to the ground and the ramps let dawn.. Timber sleepers are used for tilling the gaps in the ramps,. also for the spaces between them. • TQ assist loading, a double-purpose steel-sided crab winch is provided on the upper platform at the front of the attachment. When the nature Of the load permits, the wire is attached direct, but, should the load call for special measures, snatch blocks are used, one end being anchored to a heavy eye provided at the back of the forward platform.
Arrangements have been made so that the semi-trailer can quickly be detached from the motive unit, the upper part of the turntable being secured to the tractor portion by. a collared king-pin. To detach the semi-trailer it is necessary only to extract a locking fork and lift the trailer dear. In view of the fact that it is not always convenient to unload heavy machinery so soon as it surives on the site, this feature is of great value as it enables the tractor to he quickly released for other work. Brakes are provided on the four solid-tyred bogie wheels and these are provided with two means of control. From the tractor, the brakes are applied inthe usual way through the king-pin on the turntable, whilst a separate hand wheel on the raised platform at the front of the attachment gives an additional means of operation. The brake rods extend to a point just •forward of the bogies, and, from that point, cables are carried to an operating lever on the bogie frames. A quick-release connection is incorporated to enable the bogies easily to be wheeled clear of the frame when end-loading is required,
As previously mentioned, the overall, length of the semitrailer attachment is 33 ft. 2 ins., the main platform length is 18 ft. and the raised platform at the front has a length of 8 ft. 4 ins.
The attachment, which is to be operated in conjunction with a Scammell motive unit, is to be used largely in connection with the big hydro-electric schemes now being carried out in Scotland.