Power for the TWS425 comes from a four-cylinder, water-cooled, 45hp Kubota diesel engine. It’s not the cheapest of options but does add that reassuring ‘Kubota reliability’ factor. The high-efficiency rating of the TWS425 is down to the combination of engine and a new design of shredding mechanism.
It’s easy to check out the shredding chamber on this machine — remove two bolts and the hinged housing folds back. A safety switch ensures the machine can’t be operated with the rotor housing open. Inside, we find the hard work is done by 18 swinging hammers.
But these are no ordinary hammers. They have a blunt profile to pulverise material against the bottom anvil and are designed so they won’t jam together, yet still produce a consistent product. The hammers, with replaceable tips, run in a bush that slides on the shredder shaft to protect the shaft and enhance its lifespan. We are told the hammers are likely to last around 400 hours if shredding green waste, perhaps 100 hours if processing contaminated timber, and tip replacements cost about £15. The shredding mechanism also incorporates heavy-duty air paddles that generate positive air pressure for effective discharge of large volumes of processed material.
Feeding the TWS425 is a doddle: the funnel is huge, positioned at a good height for loading and the feed tray slopes backwards towards the throat.
At the base of the funnel, the oversized feed roller literally climbs over big pieces of material — rising to a height of up to 23cm for large timbers. Eight blades on the roller sink into the material to drag it into the shredding mechanism. Huge amounts of torque are delivered to this roller, so, no matter what you are trying to process, the roller should keep on turning, crushing and feeding. The roller blades are individually replaceable — no need to go for a new roller. Now that’s a good idea.
This shredder features another bit of clever technology. Auto back-off works in conjunction with the auto-feed control. If the auto feed control is activated, the auto back-off is also activated and the roller actually backs the material off the shredding mechanism a fraction, allowing it to accelerate quickly back to working speed and also giving the hammers a chance to cool off, albeit momentarily.
A half-length safety curtain positioned just forward of the roller means you can keep an eye on what is happening. You may not like curtains or perhaps don’t agree with short curtains, but it does remove the temptation to reach in and push the guard to one side for a better view. A safety bar is fitted around the bottom of the funnel and extends up both sides.
Another feature you will either love or hate is the electronic control. Some of you will prefer mechanical, some electrical. This machine has large control boxes either side of the machine — green for go and blue for reverse. It’s easy. The boxes are sealed and, at least on a new machine, look waterproof.
We find it hard to keep up with this machine. Being a “high throughput” shredder with air discharge it works best with dry material — contaminated wood, fence posts, plywood — even mdf offcuts and upvc window frames. It will take soft material. Freshly cut green-waste material, including hedgetrimmings, and dried-out pot plants and rootballs are no problem for it. We also find it works well with cardboard and packaging. The feed roller and shredder mechanism both have anti-wrap characteristics, so fibrous, stringy material — including brambles and briars — can be processed effectively. But don’t expect this one to reprocess partly decomposed matter from a compost heap or heavy, wet, green material that has been piled up for several days.
The discharge tube rotates through 270? and can be aimed at compost bays or directed for loading into trailers or skips. Given the degree of rotation available, material cannot be fired backwards over the working position of the operators.
The TWS425 is available in trailer version only and can be towed by a transit. Although this shredder has a list price of £30,000, expect to pay somewhere around the £25,000 mark.
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