Pitt Introduces Front-loading and Twin-oscillating-axle Semis
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TWO new additions have beej made to I the range of semi-trailer manufactured by Charles Pitt (Bartoi Stacey)
Ltd. They are the Forelo 12/14ton front-lowering ground-ley 1-loading straight-frame semi-trailer, and, the All
align 15/16-ton twin-oscillating-axle straight-frame semi-trailer.
The Forelode is designed to facilitate the loading operation of most of the loads normally carried by a normal knock-out axle drop-frame semi-trailer. Loading is from the front of the trailer, at ground level, and can be undertaken by one man.
The hydraulic landing gear comprises two pivoted tubular legs each fitted with twin landing wheels. Two-stage pushtype rams, pivoted on the chltssis, are fitted to each leg to extend thir to the " down " position. A simple nechanical lock maintains the legs in this position. A single-acting single-stage pull type ram is used to raise the legs, where, they are held in place by a self-engaging gravity lock, which is disengaged manually.
Operation of the hydraulic system is from a Power Jacks manual pump box, designed to prevent damage from overloading. The box has two-speed operation with automatic change over at a predetermined pressure to restrict physical effort to a sensible minimum, while the rate of descent is controlled by a restrictor valve as a safety precaut on All controls are situated towards the rear of the trailer to ensure a reasonable working height when the front of the unit is on the ground. The hydraulic system may also be driven from a power t e-off on the prime mover.
First stage of a typical loadi g operation is to lower the legs to the gound by means of the hand pump. Th tractive unit is then driven off and parked alongside the trailer, and the powelf take-off connected to the hydraulic. systPrn. The legs are then drawn up, the front of the semitrailer thus being lowered to the ground. After loading, the platform is raised again by the reverse operation, the prime mover is discon
nected from the hydraulic system and driven hack on to the trailer coupling, and finally the legs are raised by means of the hand pump.
At a demonstration last week a tractor and agricultural trailer were driven on to the semi-trailer, and then a heavy steel trolley was winched on to the trailer by an underfloor winch which is an available option. Finally the raising-and-lowering operation was performed while the platform carried a load of 14 tons in the form of concrete blocks. An important feature is the fact that apart from the retractable landing gear the trailer is a perfectly standard semitrailer, allowing complete interchangeability with existing trailers.
The All-align is a straight-framed oscillating axle semi-trailer inebrporating a new design of suspension which, it is claimed, requires no maintenance. Spherilastik rubber bushes are used in the pivots for front and rear swinging members in which the springs are slipper mounted. Metalastik IS. bushes are employed in torque rods locating each axle. Both models are available in lengths from 24 ft. to 27 ft., and a 10-ton version of the Forelode is also available. In all cases the main frames are 15 in. by 3-5 in. pressed channel members, reducing at the front to 7 in. deep. Internal cross members at 24-in, centres are 6-in. by 2-in steel channel welded flush to the main members, whilst outriggers at the same spacing are 6-in, deep channels tapering to 3-75 in. by 2 in. with their upper face 0.5 in. below the top of the main members. The rear cross-member is I5-in. by 3-5-in, channel and the side raves 7-in. by I-5-in. channel, raised 2 in. above the floor. The front cross-member is a 7-in. by 3-in, rolled-steel channel section in the case of the Forelode semi-trailer and a 4-in. by 2-in, rolled-steel channel on the Brakes on both models are Girling centre-pull type assemblies operated by a Clayton Dewandre upright vacuum system, with an independent hand parking-brake lever situated under the near side of the chassis, operated by a cable. Two-line air-pressure operation is available in addition to, or in place of, the vacuum system.