7 June 1996

Fast, & with 4WS now

By Andrew Faulkner

FIVE years and 3500 units on, JCB has done something rather dramatic to the Fastrac. Like self-propelled sprayers and telescopic handlers, the firms "fast" tractor is now available with four-wheel steer for improved manoeuvrability on field headlands and around farm buildings.

Turning circle, as JCB readily admits, has been a criticism levelled at the Fastrac ever since its launch in 1991.

In 1995, the firm went some way to addressing the problem with the launch of the smaller 1100 series models, the 115hp 1115 and 135hp 1135 – tractors which now account for about 50% of all Fastrac sales. The four-wheel-steer option, badged Quadtronic and only available on those 1100 models, tightens the turning circle still further.

"On 18in wide front tyres set at 72in track, the standard 1115 and 1135 Fastracs brought our turning circle down to a size comparable with other 4wd tractors in that power bracket," JCB Landpowers Richard Fox-Marrs explains.

"The new four-wheel-steer system reduces the turning circle by a further 25% – down to 10m."

That means, for the first time, there is a Fastrac capable of a "shunt-less" headland turn in a field drilled with 12m (39ft) tramlines.

So what has JCB had to tinker with to fit Quadtronic? The answer: Not too much. Other than a new rear axle centre casing and triple-section hydraulic pump – a tandem pump is standard – most of the components are "bolt-on" extras so the tractor, when stationary, looks almost identical to the standard 1100. Loading and performance capability are unaffected, JCB says.

Extra Quadronic components are an in-cab control pad, two potentiometers (positioning sensors) – one on the offside front axle and one on the offside rear -, a wiring harness, a powered track rod on the rear axle and rear swivelling hubs. There is no mechanical or hydraulic link between the two axles – just the two potentiometers which keep the control pad informed of relative positions, and adjustments are made accordingly.

For those thinking the Fastrac has just picked up a dose of four-wheel-steer technology from JCBs Loadall telescopic – it hasnt. Whereas the telehandlers use a basic two-wheel-, four-wheel- and crab-steer set-up, Quadtronic has five steering modes specifically developed for field work (see box opposite).

JCB stresses that adding four-wheel steer does not mean that the 1100 tractors are just top work machines, and should not be categorised with self-propelled hydrostatics.

"They are still heavy-draft tractors," Mr Fox-Marrs insists.

"Its just now they come with four-wheel steer, making them more manoeuvrable for all operations, not just spraying and fertiliser spreading."

&#8226 Although technically possible to adapt Quadtronic to fit the bigger 150hp+ Fastracs, JCB says it has no plans to do so.

Price of the option when fitted to the 1115 and 1135 models is £5700.


Quadtronic 4WS modes

lTwo-wheel: Rear wheels locked, front wheels turn up to 40í.

lProportional four-wheel: Rear wheels turn 20í, front wheels 40í; for every 1í movement on rear, the front moves by 2í. Likely to be most popular and gives tightest turns.

lTrue tracking four-wheel: Both wheels turn together up to 20í so run on same track – for in-tramline work.

lDelay four-wheel: Front wheels turn 15í before four-wheel-steer cuts in. Useful for fieldwork to prevent rear-end twitching.

lCrab-steer: As it suggests.

NB – 1 Headland Management System gives auto cut in and out of four-wheel steer and diff lock. 2 Over 12.5mph, Quadtronic automatically locks into two-wheel steer.

whatever the touch pad setting.

Unchartered territory for the Fastrac – Quadtronic four-wheel steer means headland loop turns are possible, rather than shunting to and fro. Inset: In-cab, Quadtronic touch pad selects one of five steering modes.