| 摘要 |
1,156,228. Vehicle hitches. CATERPILLAR TRACTOR CO. 4 Oct., 1966 [23 Oct., 1965], No. 44220/66. Heading B7T. A material handling vehicle, as described in co-pending Specification 1,116,717, comprises tractors 10, 11 supporting a dump-doored body 12 and connected to the body 12 by king-pin hitches 14, 15, each comprising a king-pin formed as a piston 18 bolted by a flange 19 to a tractor 10 or 11, and a cylinder 20 slidably embracing the piston 18 and bolted by cylinder brackets 32 to a structure 28, Fig. 3, supported by beams 34, 35 on the body 12, wherein hydraulic fluid under pressure in the cylinder 20 above the piston 18 provides a fluid bearing which sustains and raises the body 12. The cylinder 20 carries a seal 21, a perforated guide ring 22, steering arms 44, and stops 24, 26, and a support element 38 thereon is bolted to a tongue 41 on the structure 28. Each tractor has a source (not shown) of oil under pressure and supplies accumulators in the pistons 18 and also supplies a valve controlling flow of oil to the cylinder 20. The valve comprises a spool having a stem engageable by the piston 18, and a bore transmitting the cylinder pressure to the upper end of the spool, the spool also having a port registrable with the supply line so that the oil bearing is maintained. The body 12 may be raised by the opening of either of two valves provided, one in the drive cab of each tractor, which opening moves the spools so that the port is aligned with the supply line. The body 12 may be lowered by venting pressure via the two valves.
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