9 March 2001

HOWTOBUYABARGAIN…

Trailed forage harvesters

have recently been swept

aside in favour of high

capacity self-propelled

machines – but those who

want cheap chopping

performance might do well

to consider a second-hand

trailed Mengele SH40N

forager. Geoff Ashcroft

reports

FOR a trailed forage harvester to have remained virtually unchanged in its design over 11 years of production means one of two things: nobody wants them anymore, or its basic design is so good that it might be difficult to improve upon. And in the case of Mengeles SH40N trailed, flywheel forager, the latter would appear to be true.

"Its a very tough machine that can be operated with as little as 90hp, or used with the largest non-artic tractors in the country," explains Dave Bull of Mengele importer Rustons Engineering Co (RECO). "It has a very simple, but efficient driveline that ensures horsepower is not wasted, and goes straight to the chopping flywheel."

Introduced with a 1.65m wide pickup and a 12-knife flywheel in 1989, the SH40N has changed little in the last 11 years. In 1991, a wider 1.8m pickup was introduced and in 1994, the knife count was reduced to 10 following a change in nutritional advice to provide a longer chop length (12-22mm).

The machine has had colour changes too. Up to 1996, SH40Ns were a mix of red and blue; in 1997, they were all blue to dispel rumours that Massey Ferguson was buying the brand, and in 1998 the forager adopted its current blue and grey colour scheme.

Current list price of a Mengele SH40N is about £24,000 – but second-hand models range from as little as £1500 up to £13,000 according to Mengele dealer and forager specialist Western Farm Services of Knighton, Wales, which last year sold 13 second-hand SH40Ns.

With solid engineering and the ability to handle plenty of horsepower, a well-maintained SH40N offers few clues about the amount of work it has done – so a keen eye is essential when looking over the machine.

Apart from the condition of shaft guarding and yokes/joints, theres little to check at the pto. The first stop is at the end of the main driveline, where a five-V powerband connects the other end of the pto shaft with the flywheel. A genuine belt is a must, according to Mr Bull.

"Ive seen spurious belts burnt off within half a day," he warns.

Check condition of belt for cracks – machines that spend time on the road can collect small stones in the belt which are then forced out through the back of the belt by the pulleys when drive is engaged, resulting in a torn belt. Also check how much adjustment is left on the spring tensioner – its a useful indication of remaining belt life. A new belt will cost in the region of £200.

A visual inspection of the flywheel casing and chute can reveal stone damage, though the casing and chute have replaceable linings. The chute also has support stays on spring tensioners to minimise stress transfer from chute to the chassis, contributing to machine longevity.

The SH40Ns flywheel has two functions – cutting and blowing, using separate blades and paddle blowers. Take a good look at the flywheel, blades and carriers for damage, and rock the flywheel to check for excessive end-float. The flywheel sits on a threaded hub that is wound in or out to get correct shearbar clearance – its a simple, easy system, but too much movement could see blades make contact with fixed components, like the shearbar, for example.

The SH40Ns U-shaped shearbar is reversible, but when its two working edges are worn, expect to pay about £462 for a replacement bar. Blades are priced at about £72 each while paddle tips are £23 each.

Condition of the grindstone may indicate how well the machine has been looked after. A worn stone shows regular sharpening has taken place. Its a good sign, and indicates someone has looked after the blades, but the downside is that a replacement stone will set you back £335.

Drive to the rest of the machine is from a chain on the front of the flywheel. It puts power into the feed roller gearbox and also drives a hydraulic pump for the machines self-contained hydraulic system.

Gearbox and hydraulic system oils should be changed annually and theres a washable filter in the hydraulic tank. Every forager comes with four gears for varying feed roller speed – two will be in use, the other two should be pinned to a stub shaft.

Every bearing and driveshaft joint can be greased on the SH40N – but the feed roller driveshafts are the hardest to grease when the pickup is in place. They also need daily greasing and these are likely to give up first. These shafts also contain slip clutches, which protect the gearbox in the event of a blockage.

With the pickup removed, look into the feed rollers for damaged teeth and also check the condition of the parallelogram linkage that keeps the top two rollers in check. Feed roller bearings are outside of the feed chamber and are easy to check or replace.

According to Western Farm Services, theres little to fault the Mengeles pickup. Auger flights should be free of damage and the pickup reel should have tines and tine guides in place.

In-cab controls operate electro-hydraulic solenoids on the hydraulic system – theres little to check; they either work or they dont. Finally, run the machine to check for unusual noises, knocks or chattering joints. Only then will you know if youve found a bargain.

Left: Powerband should be inspected for wear; adjustment remaining on spring tensioner is the key to remaining belt life.

Below: Dual-action flywheel does cutting and blowing; check blade condition and clearance between paddles and flywheel casing.

Electronic solenoid controls for the foragers functions are reasonably trouble-free – they either work or they dont.

Left: U-shaped shearbar is reversible, but when its working edges are worn, expect to pay about £462 for a replacement bar.

Reco Mengele SH40N trailed forage harvester at work.