9 June 1995

trailer cast-offs a good buy


Increased use of big bales and big bags has led to rising farmer demand for longer flatbed trailers. One possible source is cast-offs from the road haulage industry. Andrew Faulkner reports

BUYING an ageing articulated trailer from a commercial vehicle auction has much to commend it: Payloads are high, the chassis and running gear engineering is built for 400hp tractor units pulling at 60mph+, and prices are low.

For example, a 30ft long flatbed trailer suitable for carting big bales and 1t fertiliser/seed bags, can be picked up at auction for as little as £300. To that has to be added conversion costs, but there are still significant savings to be made against buying an "off-the-shelf", traditional farm model. As with all auction buying, however, there are pitfalls for the unwary.

Merrick Loggin of Merrick Loggin Trailers, has been modifying commercial trailers for agricultural use for the past 23 years; he now specialises in building new trailer bodies on commercial running gear. Here he provides tips on what to look for when buying a trailer, and how to convert it:

Trailer type: A 15 to 20-year-old tandem axle, 30ft long flatbed is a typical example of what might be found for about £500. For farm use, 30ft is a sensible compromise between capacity and manoeuvrability; the road industry standard, a 40ft long bed, will be too ungainly for most yards and lanes, and give the average summer student palpitations. Maximum gross weight of a tandem axle trailer is 18,290kg, with a max combination train weight of 24,390kg.

"Tandems converted to four wheelers make the best farm flatbeds," Mr Loggin says.

"This is achieved by removing the rearmost axle and using it to make a convertor dolly for the front of the trailer. That leaves the remaining axle about 10ft from the back of the trailer, resulting in a better turning circle than the original tandem.

"A braked, four-wheeled trailer of this spec can legally carry about 15t, assuming an unladen weight of 3t. But we dont recommend more than 10-12t; the four-wheel design means theres insufficient weight transfer onto the pulling tractors axle to go to heavier weights."

Floor: Hardwood floors are the norm for commercial specs – a significant benefit of buying this type of trailer; it doesnt warp or rot in the same way as its softer timber counterpart. Minor blemishes are acceptable but avoid examples with gaping holes.

Chassis: Inspection from one end should reveal any twists in the chassis line. "Once a chassis/bed has been twisted, its almost impossible to straighten," Mr Loggin says.

Lights: The system will almost certainly be incomplete and 24V. Cost of re-cladding in 12v is about £40. Check for side marker lights and reflectors. This is an understandable favourite with the motoring constabulary, because when pulling across a main road, rear lighting doesnt show to oncoming motorists.

Brakes: These will be air-operated and need converting to a hydraulic system for operation by most farm tractors.

The less scrupulous haulage operator may have removed the trailers brake shoes before sending it to auction, so scramble through the running gear for a look. Avoid examples which have been tampered with.

A simple check is to drain the air tanks, apply the hand brake, and try to rock the wheel by hand – if the brakes are there, there will be no movement.

Check for cracks

While grovelling underneath the bed, check for cracks in the suspension springs and rust/rot around the king pin mounting frame at the front of the trailer.

Tyres: Older trailers tend to come on 16ply 10R20 twin tyres. Condition is unlikely to be a problem, because commercial tyres are suitable for regrooving and travel further in a day than most farm tyres will do in a year.

Plate and test certificate: Not as important as they may seem because overall condition is of more value than age. An agricultural trailer does not need a test certificate. Note: Rules for farm trailers towed at speeds over 20mph differ from those for trailers travelling at less than 20mph.

&#8226 For full details of weight, braking, lighting and speed related requirements for agricultural trailers, refer to the NFUs Orderline documents. They are available free to NFU members (0345-585324).

&#8226 For correct construction procedure for building convertor dollies, refer to Guidelines for the Manufacture and Operation of Convertor Dollies used in Agriculture, Horticulture and Forestry.

Commercial running gear is built to last, but will need modification; brake cams require hydraulic operation rather than air power. Inspect leaf springs for cracks.

This 26ft long flatbed is a typical ex-commercial vehicle auction trailer. Built in 1979, its last test certificate expired in 1992 and auction value is about £400. To convert for farm use, the most expensive item needed is a convertor dolly axle for the front end (£750). Brakes and lights will also need attention. Merrick Loggin (inset) of Northants-based Merrick Loggin Trailers will carry out complete conversion for £1000.

When fitted permanently, the convertor dolly allows the trailers jack legs to be removed. The most common omission from farm conversions is a convertor plate; this should show conversion date, max gross weight of trailer, max axle weight of dolly and max weight imposed on towing vehicle.

16-ply commercial tyres can be regrooved to improve tread and are almost puncture resistant. Typical pressures are 110-120psi.

Side amber reflectors can save lives. When crossing a road at night, rear and front lights may not be visible to oncoming traffic. These side reflectors may be the only sign that the road is blocked.

Any lights left on an auction-sourced trailer are a bonus – most will have been robbed. Fitting an off-the-shelf lighting board may be a tempting low cost option, but is probably illegal. Check correct positioning and number of lights needed for the length of trailer.