Merriworth offers Metalastic on singles and tandems
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MERRIWORTH announces this week a new range of rubber suspension units for trailers. Single and tandem-axle versions are to be offered with Merriworth's own range or as kits for tankers and other manufacturers' vehicles.
Apart from the superior ride to leaf-spring units Merriworth claims a good degree of articulation for the tandem bogie, making it suitable for on/ off road service or for operation on the French road-rail kangaroo system. The articulation available is claimed sufficient to permit a trailer to negotiate the keep ramps onto rail trucks without the wheels leaving the ramp surface.
The tandem-axle version, which will be exhibited at Earls Court fitted to a .fiatplatform semi-trailer, is based around a central frame. Four swinging axle arms pivot from the frame ends, two to each axle and a long balance beam pivots about the vertical centre-line of the frame and runs above the axle arms. Each axle is located by its two arms; one rigidly mounted the other pivoted to it. At each side of the suspension a rigidly mounted arm is opposite a pivoted one on the other axle.
Merriworth claims that using a pivoted and a fixed arm on each axle eliminates axle wind-up during vehicle roll.
The axle arms also serve as mountings for the four Metalastik rubber springs which are sandwiched between the axle arms and the balance beam ends.
As axle deflection increases, the geometry of the linkage alters the load bias on the Metalastik spring from shear to compression to provide the optimim increase of spring rate for good ride in laden as well as unladen condition. Axle arms are constructed to absorb brake torque reaction and side loading and they locate the axles without the need for Aframes, panhard rods oother linkage.
The complete tandemaxle unit has only eight rubber-bushed pivot points and they do not require lubrication.
A further tandem-axle version, but with greater articulation and aimed at the retracting bogie (Villiers type) tipping semi-trailer is on the drawing board.
Merriworth also announces this week details of its show exhibits whch include three trailer prototypes. The first is a TIR semi-trailer with full-height van-style rear doors to provide easier access than with the sheets and tailboard usually employed. The doors, like the bulkhead and side boards, are made of pressed steel with pressed-in stiffening ribs. Each sideboard has a single central locking handle which operates both locks.
A 2.1m (6.8 ft) widespread version of the tandem-axle rubber suspension will be featured on a 12m (40 ft) flat-platform trailer, and there will also be a four-axle drawbar trailer especially designed for Swedish logging operation. Plated to 32.5 tonnes (32 tons) gross trailer weight, the 10.2m (33.5ft) long skeletal has transverse bolsters to support the logs. Upright stanchions at each side of the bolster restrain the load laterally and are swung down to act as unloading ramps. The tailer is carried on two-axle bogies and the outfit uses Rubery Owen axles and suspension.