30 June 1995

Trimmer is put to test

Spearhead Machinery first entered the hedger market with a contractors model in November 94. At this years Royal Show it will introduce a smaller, farmers machine – the Twiga 5. Here David Cham, farm foreman at FWs Easton Lodge, gets a sneak preview, while

Andrew Faulkner takes notes

LOVE it or loathe it, hedge-trimming is one of those jobs that demands an opinion.

For some, pruning the nations hedges is a task to be savoured and preserved. For others, however, the job means hours of tedium, country lane confrontations with scowling school-run mums, and neck ache from craning around tractor cabin pillars.

Hedger manufacturers have done much to improve the operators lot – cranked arms for better visibility and electro-hydraulic /single-lever joystick operation for more precise hedger control, are two examples.

And at this years Royal Show, Spearhead Machinery will launch its Twiga 5 model – baby brother to the contractor Twiga 6 – which is claimed to take hedger development a stage further.

In its most basic form (£7995), the Twiga 5 is little different to any other standard four-lever, cable-controlled hedger. It is a mid-range, three-point linkage mounted machine with a 1.2m (4ft) wide cutting head and maximum horizontal reach of 5.2m (17ft).

But move up just one step in spec and things start to get interesting. For an extra £800, the spool block cables are controlled by a single-lever joystick that operates head up/down and in/out. Press a solenoid diverter switch in the end of the lever and one of the spools is converted to head angle operation. A third spool, operated by a separate lever, controls the hedger arms base plate; once set, this is rarely touched.

Clever but still not particularly dramatic – the best bit is still to come: All six hydraulic rams on the hedger arm are plumbed in in such a way that they operate in tandem. This gives auto parallel movement of the hedger head when the operator either moves it up/down or in/out; he doesnt need to tweak one arm section to compensate for moving the other.

So is the Twiga 5s mid-spec control system a step forward, or merely marketing hype? Here David Cham, who works with farmers weekly farms manager John Lambkin at Easton Lodge arable unit, gives his verdict through words and pictures

Initial machine impressions

Solid British engineering with plenty of steel in all the right places, says David Cham. Pipework is tidily clamped into position, and the head hoods curved edge should allow smooth break-back without digging into dirt.

Mounting the head motor on the inner side is sensible because it means no snagging when trimming into hedge bottoms.

Only grumble: Demo machine was fitted with skimpy 75mm (3in) diameter head roller; however, sturdier 150mm (6in) version can be specified at little extra cost (£35).

Hitching on and off

Scores well here. Hitching on/off should be a 5min job, taking no longer than coupling up to any shaft-driven, linkage-mounted machine. Stability comes from combination of two extra tie bars – conventional top links – and tractors standard stabilisers.

Would be no groans if manager needed a hitch off and on in the same day. Different story with some bracket-mounted machines.

Maintenance

Standard hedger check points apply. Sight gauge for 42.5gal oil reservoir is sited on the front of the tank, whereas it would be more readily visible at the rear. Filter condition indicator, which turns red when blocked, is a nice touch.

Total of 19 bearing and pivot points (excluding pto shaft) that need greasing are a chore, but no better or worse than any other machine. At least all pivot pins are housed in bushes.

From the drivers seat

The operating console contains four controls: Main joystick, base plate lever, rotor engage and a head float switch for verge mowing.

Having recently upgraded to state-of-the-art electro-hydraulic finger switches on Easton Lodges machine, moving back to cable controls seems somewhat retrograde. But the Spearhead joystick, combined with parallel linkage, is a revelation.

For siding work, once the head angle and height is set at the start of the run, the only movement is to tweak the joystick from side to side – pushing the head in and out of the hedge – to compensate for any steering errors. There is no need to adjust the first arm section because this happens automatically.

Likewise for topping. Lifting the head up and down or pushing it away and towards the tractor makes no difference to head angle – the parallel linkage takes care of that.

Driver feedback from joystick/cable movement is relatively progressive and less abrupt than electro-hydraulic alternative, which Spearhead also offers. Only drawback of the cable system is that after several hours use, the wrists begin to ache.

To counter this criticism, Spearhead will introduce a hydraulic servo link between joystick and spool block at this years Royal Show.

Moving this joystick operates four plungers in a low pressure hydraulic circuit that, in turn, operate the spools in the hedgers high pressure circuit.

Overall impression

A hedger is only as good as its control system and head, and the Twiga 5 has few shortcomings in either area. Its cranked blade leaves a tidy finish in both hedge and grass, and the joystick control/parallel linkage system is a peach. Add the forward reach and "oil-over-oil" joystick options, and its a machine I could get used to, says David Cham. Wheres your cheque book, Mr Lambkin…?