Review - Woodchippers

Three of the latest models tested with willow timber at Derby College - Sally Drury shares the results.

Timberwolf TW230DHB
Timberwolf TW230DHB

Tested This Issue

Timberwolf TW230DHB

GreenMech Arborist 190

GreenMech ArbTrak 190

The Review Panel

Matthew Ford, arboricuture trainer and assessor, Broomfield Hall Campus, Derby College

Douglas Porter, former Derby College student

As a professional arborist you want to get the job done quickly and cleanly. So why spend time loading branches onto a lorry, lashing them down and making three or four trips back to the depot when you can chip the timber and reduce the volume for single-trip transportation or, better still, leave the chippings on site, blown back into woodland? The woodchipper has become indispensable for anyone involved in tree maintenance.

In this test we take three of the latest models - the Timberwolf TW230DHB sub-750kg and the GreenMech Arborist 190 as a road tow model and also self-propelled on tracks - to the Broomfield Hall Campus of Derby College.

There we ask Matthew Ford to put the machines through their paces. Before coming to the college as arboriculture trainer and assessor, Ford worked in the industry, where he used Jenson woodchippers. Having no previous experience of either GreenMech or Timberwolf, he is well placed to review the new models. We were also joined for part of the test by Douglas Porter, who having studied at Derby is now a tree surgeon.

The weather on the test days was dry and sunny. Willow timber was used through all three machines.

Timberwolf TW230DHB

It looks like Timberwolf's famous TW150, often seen towed on motorways and around towns, but this chipper is a step up. For starters, it is faster than the 150. It is also stronger and much easier to service. Yet despite the improvements, the 230 remains a sub-750kg chipper that can be towed without the need for an additional trailer licence.

The weight is crucial for many. Practical arboriculture, by its nature, is a younger person's business. But chippers still need to be towed. The cut-off point for legal towing without extra tests is 750kg. This one weighs just 749kg, and that is with a full fuel tank and all the fluids.

A larger and more powerful chipping rotor lies at the heart of the new machine, ensuring that everything we throw at it is neatly chipped and thoroughly dispersed. Although Ford describes the GreenMech as having "a slightly more fluid intake", we find the TW230 takes, handles and processes the timber well.

"There is no side swipe of the timber as it is fed in but there is a bit of bounce," says Ford. He appreciates the open-top funnel, large chipper throat and wide rollers. Throughput is fast and the ejection of chips is remarkable. "This really fires the chips out," he adds. "We have thrown them well into the wood and out of the way." The chips are uniform, with potential for use as woodchips.

With a wider axle and a deeper chassis beam, the TW230 is stable on the ground. Access to the rotor, anvil and blades is simple, but what Ford really likes is the remote greasing. "It's great that you don't have to go into the machine for daily maintenance - that's a definite advantage," he points out. "You don't want to spend minutes out of your day hunting for the grease nipples."

During the test, the bottom bar tripped once but the machine was up and running again quickly. Porter finds the machine easy to control, including forward/reverse movement of the rollers, and he is impressed with the crushing power of the rollers. But more important for him is the weight of the machine. "I don't have a trailer licence yet so I would be looking for a sub-750kg machine," he explains.

Timberwolf has paid a lot of attention to detail - witness the auto-latch cast tow head and LED light board. We reckon that tree surgeons, contractors, local authorities and hire shops will appreciate both the machine and the price. Ford says: "The price is a big advantage, especially for anyone just starting up a business."


Capacity 160mm diameter (6.3in)

Engine 35hp four-cylinder, water-cooled Kubota diesel

Drive Direct, three belts

Feed roller Twin horizontal hydraulic

Blades 135x100mm, double sided, fully hardened

Rotor speed 1,920rpm

Power control Auto feed control

Discharge chute rotation 270 degs

Greasing Remote

Fuel capacity 18 litres

Transport length 3.3m

Width 1.51m

Height 2.18m

Weight 749kg including full tank of fuel and other fluids

List price £16,995 + VAT

Tel Timberwolf - 01449 765800

GreenMech Arborist 190

A big brother for the well-established GreenMech 150, the Arborist 190 soon has Ford reaching into his pockets. "If I had the money, I would buy it today," he declares.

There is a lot about this machine that impresses but, of course, with a 190mm capacity it is a bigger machine and records a towable weight of 1,260kg. Ford is quick to spot features that make it "towable".

"Look at the tailgate - it's epic," he exclaims. "When you tow behind different vehicles, you normally have to change everything over. All you have to do here is slot in the number plate. The adjustable drawbar makes hitching easy, so you can get to work quickly. The chassis looks strong and the lights are all nicely protected so they shouldn't get damaged when reversing in tight spaces."

But perhaps the biggest draw about the new 190 is its modular build. It is rigid, yet it is built in blocks. The chassis is a module, as are the mudguards and the drawbar. The engine is a module, so is the chipper box, so is the infeed. With laser cutting, GreenMech is "slotting and bolting" metal together rather than welding. It means that the various parts can be removed for easy maintenance or be replaced in the event of damage.

Maintenance has been simplified with a slide-out radiator and GreenMech's "turn and use again" disc blades. These are tolerant of contaminants and have a working life of up to 900 or 1,000 hours.

Operation has been kept simple. Ford presents the wood to the rollers and the chipper does the rest, leaving Ford to fetch the next branch. These are vertical-feed rollers and the timber seems to flow in. However, there is a "get-out-jail card"

- a clutch that can be disengaged so any jammed material can be backed out. We don't have to use it. Also, with there being no bottom bar, we experience no tripping.

We appreciate the low noise from the engine. An extra fan, employed for cooling the chamber, helps to remove the chips and means that the engine can be run at lower revs. Overall, Ford is impressed. "It's simple to use. I like the grab handles to help you haul the unit into place on site. It is a good loading angle and the feedability is fluid - it almost feeds itself."

Despite willow being a fibrous material, the quality of chips is good. Throw may be better on the Timberwolf, but certainly the chips would make it into the back of a lorry.


Capacity 190mm diameter (7.5in)

Engine 45hp Kubota diesel

Infeed throat opening 190x280mm

Infeed funnel opening 1.2x0.84m

Feed roller Twin vertical hydraulic

Number of blades Four disc cutters

Flywheel Disc blade

Rotor speed 1,500rpm

Power control No stress

Noise level (sound power) LWA: 116dB(A); LPA: 92dB(A)

Fuel capacity 27 litres

Tyres 175R13C

Transport length 3.99m

Width 1.44m

Height 2.7m

Weight 1,260kg

List price £21,750 + VAT

Tel GreenMech - 01789 400044

GreenMech ArbTrak 190

This unit enjoys the same powerful engine as the road tow version, the same 120x84cm infeed chute and 190x280mm throat, is as simple to operate and rapidly disposes of material in the same fluid manner.

It differs by having tracks instead of tyres. The downside is that it has to be transported by trailer, but there are excellent lashing points. The upside is that it goes to hard-to-reach locations instead of you having to bring the timber to the machine.

A platform at the rear of the chipper gives the operator a commanding view of the ground ahead, while stick-steer levers allow forward/reverse travel and turning. Two handles provide something to hang onto while moving, but this only leaves your thumbs free to control movement.

Because the levers need to return to the "stop" position immediately they are released, they have powerful springs behind them. That makes them incredibly stiff. "It's a good machine to steer but it makes your thumbs ache after a while," says Ford.


As for the towed version above, except:

Fuel capacity 31 litres

Transport length 3.23m

Width 1.41m

Height 2.61m

Weight 1,600kg

Additional features Tracks instead of tyres

List price £29,990 + VAT

Tel GreenMech - 01789 400044.

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