AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

Air Springs for Eagle Trailers

22nd August 1958, Page 57
22nd August 1958
Page 57
Page 57, 22nd August 1958 — Air Springs for Eagle Trailers
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

INDICATIVE of growing interest in air-suspension systems by trailer manufacturers is the news that of four semi-trailers to be shown by the Eagle Engineering Co., Ltd., Warwick, at the Commercial Motor Show next month, three will have springs of this type to the design of the Andre Rubber Co.

The air-sprung exhibits will consist of two platform semitrailers and a 3,200-gal. frameless tanker. The first of the platform semi-trailers, now nearing completion, is being built for Reed Transport, Ltd., to carry baled paper.

Air springing has been specified because the semi-trailers used by this operator usually carry loads in only one direction and it is thought that when the semitrailer is running unladen this suspension system will be less subject to wear than normal leaf-spring layouts.

The semi-trailer itself is notable in that it is designed to carry a payload of 164 tons when coupled to a Foden FGTU6/20 tractor. The weight of the semi-trailer has been kept down to 3 tons 3 cwt., even though a double diagonally boarded wooden deck is specified.

The frame is of bolted construction, with two longitudinal inner members 8 in. deep, with 3-in, flanges, and two 7-in.-deep outer members. An interesting weight-saving feature is the use of tubeless tyres. Those fitted are Firestone 10.00-22.5 in. (12 ply) and the total saving over conventional types is 1 cwt.

Welded to the two main members of the frame is a substantial sub-frame to carry the rear bogie. This is braced by two struts running from the bottom of the structure •to join the main frame behind the vertical landing gear.

Two-compartment Andre air-pillows are used. They are 5 ft. 6 in. long and in. wide, and for the Eagle application are set to an installed height of 6 in. The pillow on each side is sandwiched between a plate mounted on the bottom of the sub-frame and a welded-steel surge tank with a capacity of 1,150 cu. in..' capable of permitting a frequency of 106 c.p.m. laden. Two semi-circular cradles are incorporated in the bottom of each surge tank to receive the tandem tubular axles, the tanks thus acting as a beam to locate the Odes. Caps are bolted in position to secure each axle.

Transfer of stress from the axles to the tanks when one wheel rises or ,falls in relation to the other is avoided by the provision of a rubber bush between these components.

For location under acceleration and braking forces, triangular pressings are welded to the leading edges of each axle tube. at the centre line. These horizontal members are carried forward to cradles, suspended from the frame, where they are mounted in large Silentbloc hushes which cater for forces arising from the rise and fall of the wheels, side thrust when cornering and the movement of one axle relative to the other.

Horizontal forces occurring during braking are controlled by rubber compression washers fitted at the front of the main bushes.

Damping for the suspension is provided by single telescopic shock absorbers fitted on each side of the bogie and sloped inwards to reduce roll: Rebound is controlled by two vertical rods rigidly secured to brackets on the sub-frame, passing through eyes welded to the side of the surge tanks. At the end of each rod a rubber buffer is fitted, which, being below the eye, can check excessive bounce.

The height-control and levelling valve for each pillow is operated through a linkage attached to the surge tank at the centre line of the bogie. The setting of the valves gives a 10-second delay and a plus or minus 4 in. deflection of the pillow is required to cause them to open.

Air pressure is provided from a 3,500-cu.-in. reservoir fed in its turn from the reservoir for the two-pipeline airpressure brakes. A non-return valve in the line between the two air tanks is set to pass air only when the pressure in the braking system has reached 65 p.s.i., thus ensuring that the action of the suspension will not endanger brake efficiency.

Capable of carrying up to 20 tons, the air-pillows used are working well within their limits on the Eagle bogie, for the imposed load should not exceed 15 tons 12+ cwt.

The pillows are unprotected, as experience has shown that when mounted in this position they are not subjected to damage by stones and other debris thrown up by the Wheels. However, should they be fractured or should any part of the air supply fail, the provision of solid-rubber pads inside the pillows themselves will enable the semi-trailer to continue in operation until the damage has been repaired.

Tags

Organisations: US Federal Reserve

comments powered by Disqus