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BOW TO GT A TIP-TOP

2nd June 1972, Page 50
2nd June 1972
Page 50
Page 51
Page 50, 2nd June 1972 — BOW TO GT A TIP-TOP
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TIR TRAILER by Martin Hayes , the job I visited Mr Laurie Caen, sales Idirector of Merriworth (Engineering) Ltd, who ran over some of the design features which, trailer manufacturers — and Merriworth in particular — build-in for the most efficient operating characteristics. These are the points he raised; most of them are relatively minor in themselves but when put together make the difference between a trailer which just meets the regulations and one which can increase an operator's productivity at low cost.

The familiar blue TIR plate (picture 1) can be fitted with a pivoted red bar which is used to cancel the TIR plate when the trailer is not operating under a full carnet. This is secured with a wing-nut and can easily be altered by the driver.

Dropsides (picture 1) are made of specially treated 18mm ply which can be painted without the paint soaking in. A recessed steel panel is inserted in the centre to house the bar and sliding rings. This feature allows an internal trailer-width of 7ft I Ifin, which means two metric pallets can be carried across the width of the trailer.

Many types of docking handle are used by trailer manufacturers but Merriworth has opted for the slipper type (picture 2)

because of its simplicity and trouble free service. A recent innovation is the fitting of a chain and ring which enables the sealing cords to be kept captive and prevents the lifting of the handles once the curtain has been sealed.

Two-piece sliding rings (picture 3) are now required by the TIR authorities. The bar which separates the oval ring must be cast in and not welded. Mr Collen was adamant about the advantages of the sliding ring design over other forms of fastening.

As staples the most common alternative to rings — have to be mounted proud of the dropside, they are easily broken off in minor accidents. Just one broken staple can mean the whole vehicle being held up for a repair because the seal is broken. Sliding rings, on the other hand, can move on impact and the worst damage is usually to the mounting bar which may bend slightly out of alignment. When building a trailer, Merriworth includes a few extra rings which can be used in the event of localized damage. As with much of the minor damage which can affect TIR trailers, the difference between rings and staples for fastening tilts can be in obviating expensive time off the road at some remote border-crossing point wait ing for an inexpensive repair.

One of the most common problems which affects TIR trailers is movement of the superstructure. This causes wear to the tilt and in severe cases can tear holes in the sheeting, thus leading to a failure to comply with the TIR regulations. The main reason for movement is that any socket fitted to the side of the trailer to accept the superstructure pillar must have a degree of free play to allow the pillar to be inserted and removed. Any such free play at the socket is magnified to allow considerable movement at a height of 20ft. Merriworth has now come up with a cheap and simple answer to the problem which may well be copied by other manufacturers. This is a device, basically consisting of a wedge, which locks solid in a socket when the vehicle is on the move (picture 4) but can be freed instantly with a tap on the base of the wedge. When the vehicle moves off, road vibration causes the wedge to lock solid. Pillar movement is said to be virtually eliminated by this method which adds less than £30 to the cost of a 40ft trailer.

In addition to lashing points fitted to the trailer chassis for securing the trailer in the holds of roll-on/roll-off ferries, the cargo

inside the trailer must also be secured firmly. Standard fittings on all Merriworth trailers are a series of internal lashing rings (picture 5) fitted down the sides of the trailer deck. An exclusive feature of these rings is that they are able to rotate through 360deg to accept securing ropes from any angle. They are recessed and fold down when not in use.

First introduced (by Merriworth) some years ago, the "open-span" design of superstructure has now been adopted by many trailer manufacturers. The design incorporates a header rail which enables intermediate pillars to be removed without the roof collapsing (picture 6). On a 40ft trailer it is possible to take out half the side or the whole side at once or the whole or part of the roof. The side-members and roof cross-bearer are locked together by a special mechanism (picture 7) which is spring-loaded and can be released or locked in seconds. These devices, which also help to reduce movement in the superstructure, are claimed to have played an important part in reducing the time taken to strip the trailer. Normal designs can take up to two hours to strip but the Merriworth design is said to be capable of being made ready for

loading or unloading in as little as 15 minutes.

Timber roof laths have been retained by Merriworth because they are strong enough to allow the driver to walk on them (picture 8). This, too, speeds up the job of removing or fitting the tilt cover. Like all the laths in Merriworth trailers, the roof members have machine-rounded edges to ensure that drivers do not get splinters when handling them.

Merriworth's use of a Dutch-made pvc / polyester material is an aid to making the tilt as easy as possible to handle under all conditions. This material retains its supple ness however hot or cold the weather, whereas the pvc /nylon which is often used by other manufacturers tends to become stiff in cold weather. The Dutch manufacturer of Merriworth's material is currently developing a cleaning solution for it.

The one question any operator will want answered about innovations in design is: how much will they cost? Mr Callen is quick to emphasize that all the items he has listed could be included in the normal £2000 to £2300 price tag for a 40ft TIR tilt trailer.

Mr Collen — who is indicating design features to Mr George Steel (left) of Smith of Maddiston Ltd and Mr Bob Wilson (right) of D. B. Wilson and Co. Ltd. (picture 9) — reckons on a trailer life of between 10 and 15 years. He points out that all Merriworth trailers could be uprated for 38 or 44-ton operation....


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