Power Steering fo r Long-load Dolly
Page 44
If you've noticed an error in this article please click here to report it so we can fix it.
DELIVERY time for 10 reinforcedconcrete girders used in the Medway fly-over crossing the M20 motorway was cut from six weeks to two by installing hydraulic power steering to the front four wheels of the rear dolly of the outfit used by Annis and Co., Ltd., Hayes, Middx., for the job. The girders were up to 124 ft. long and weighed up to 120 tons and were transported from Childerditch, near Ilford, through London to Rochester.
In its original form, with the wheels turned manually, the outfit would have taken up to an hour to negotiate a roundabout, and its movement would have been limited to Sundays only. Annis found that the time taken to negotiate roundabouts after the dollys were modified was about five minutes and the traffic delays were so reduced that the police allowed the girders to be moved at night as well as at week-ends. This meant that they were delivered in only two weeks— a two-day journey for each being cut to II hours.
Power Jacks, Ltd., of Acton, designed the hydraulic steering system using two standard 7-ton hydraulic rams. These were built into the dolly frame and operated a cable steering installation. Hydraulic pressure was supplied by a diesel engine-driven pump through a series of valves and was controlled by levers mounted at the rear of the dolly, one on each side.