The rapid evolution of four-rotor rakes means that earlier models are available secondhand at bargain prices. British machinery writer Nick Fone has made a checklist for assessing their condition.
With forage harvester appetites seemingly in an ever-increasing upward spiral, keeping them well fed can be something of a challenge, particularly in lighter cuts of grass.
To deal with the issue various manufacturers have, over the years, stretched the wingspan of their centre-discharge swathers by adding an extra brace of rotors. It’s rare now to see serious silage operators with anything less than a four-rotor rake, and some have even taken it one step further, with Krone’s monstrous six-rotor Swadro 2000 capable of taking up to 19m of grass in one swipe.
While four-rotor rakes might now be available in all colours of the rainbow, it was Claas’s Liner 3000 that first began to sell in big numbers. Launched in 1999, it could cover a 9.9m working width and quickly proved the concept worked as a means of boosting forager capacity.
Ten years on, the Liner 4000 followed – a bigger, more complex machine with larger cam tracks, a praying mantis-like folding mechanism, and the ability to gather up to 15m of grass in one sweep. Then in 2011 the 3000 was replaced by the 3500. The same working width, it had beefier, splined tine arms rather than the ‘lemon tube’ used previously and the ability to lift individual rotors to deal with angled headlands and obstacles.
It wasn’t long before that was superseded by the 3600. A redesigned frame for the front rotors meant there was no longer any need to remove the uppermost tine arms to keep transport heights sensible.
It was also ISObus compatible so purchasers didn’t necessarily have to shell out for a control box, although the lead to connect the tractor to the rake wasn’t cheap. Bear this in mind if you’re looking at a used machine originally sold without a box – if you haven’t already got an ISObus controller there will be a considerable extra sum to shell out to get one.
Because these four-star Liners have been on the market for more than 20 years – as well as Claas’s keenness to push them as a means of upping chopper output – it is white and lime-green machines you see most of. That’s reflected in the secondhand stock in dealer yards.
A new four-rotor Liner is likely to set you back anywhere between £50,000 and £65,000 (NZ$100,000 and $130,000) but there isn’t necessarily a huge demand for them secondhand because they are typically viewed as a ‘contractor’s machine’. That means if you’ve got a big enough tractor and the field sizes that’ll accommodate it, you’re in a buyer’s market and there are bargains to be found.
In addition to the obvious advantages in output their wider working widths bring, four-rotor rakes can help foragers, balers, and forage wagons maintain decent chop quality thanks to their ability to present a decent-shaped swath even in light crops. Care and attention needs to be paid to how it’s done, though, as there’s nothing that’ll annoy an already inherently grumpy chopper driver more than a ropey old row of grass. (See ‘A Knotty Issue’ box.)
Of course, their extra width also means there’s less traffic across the fields and the tug tractor will be clocking fewer miles. However, they’re not for everyone – narrow lanes and small field sizes inevitably mean they’re not a one-size-fits-all solution.
To get an idea of what you need to look out for in a secondhand swather we sought expert advice from the team at Claas Western in Frome, Somerset – one of the biggest outlets for four-rotor Liners.
Tine arms
First, and possibly most obviously, look out for bent tine arms. These are purpose-made to fold on impact at the point ahead of where they slot into the section that is carried by the cam track. It’s a feature Claas says is designed to protect the delicate internal workings of the rotor hub. Replacements come in about the $180 mark.
Grab hold of each tine arm to assess it for wear between the splined shaft and the outer sleeve. Expect a bit of play but anything more than 50-70mm at the shaft end needs further investigation. Excessive slop means the arm drops with each revolution, resulting in the tines digging deeper than they should and causing soil contamination.
There is a re-sleeving kit that involves fitting short outer-arm sections, sleeves for the inners, and new spring clips. At about $11,000 for a full rake’s worth (48 arms) it’s not a cheap option but is less expensive and time-consuming than stripping the complete rotor head down and replacing each entire arm.
The over-centre spring clips that secure the arms in their splined slot can wear at the point their folded shoulders pass through their mounting points. If not spotted they’ll break off and shed the arm in question into the swath with the inevitable result that the forager finds them or they end up in a bale. Replacement spring clips come in at about $40.
Busted or buckled spring clips can also come about as a result of frost damage. If rakes are stored outside folded up, water can run down inside the tube, and when it freezes it can pop the tine arms out of their splined slot, damaging the clips.
Replacements for broken and missing tines cost about $20.
Cam tracks
With the rake unfolded, turn each rotor and at the same time twist each tine arm. If they rotate further than they’re designed to at that given point in their cam cycle or there is any clunking, it indicates the cam track may have significant wear or has sustained damage at some point.
Generally they’re pretty bomb-proof and rarely give trouble but it’s worth pulling out the Allen-headed stud in the top of each rotor head to check the oil level and condition. It’s not uncommon to see a bit of weeping around the point where the tine arm shaft joins the cam track (left). It’s a relatively simple fix involving changing a lip seal, but it does mean pulling apart the rotor head. It’s not uncommon to find the reservoir filled with semi-fluid grease as a short-term means of limiting lubricant losses.
Rotor carriages and running gear
Fabricated from a mix of folded flat bar and box-section, the rotor carriages have a simple coil spring arrangement at the beam pivot that pulls the front up at an angle when the carriage is lifted. This means when lowered back into work, the rear wheels make contact with the ground first in a ‘jet effect’, avoiding damage to the tines and excessive digging in.
The threaded bar that locates and tensions the coil spring can shear off so it’s not uncommon to see baler twine employed as a makeshift spring retainer.
Inevitably the carriages’ swivelling castor wheels suffer wear. Obviously, check the bearings for play but also the pivot bushes – an easy fix that’ll soak up a fair bit of slop.
The carriage frame itself is put under a fair amount of duress at times and can crack in places, particularly the box-section crossmembers. Look out for welding here – not always done in the most sympathetic manner.
Main beam and axles
By the nature of their job, four-rotor rakes will have encountered a fairly hefty workload, and stress fractures are not uncommon on Liners.
The main beam that forms the backbone of the machine carries the entire weight of the rake and this is all transferred to the transport wheels when the rotors are lifted out of work. The plate around the bushes that house the two pivot pins linking the chassis to the axle had a tendency to crack on older models. Later versions had an offset circular plate welded on at this point to take the strain – check for any cracks or repairs.
Likewise check the area around the point where the axle joins the vertical box-section uprights. Although gusseted, these can often crack.
At the headstock, check the vertical beam the first pto carrier bearing is mounted on as overzealous operators turning too tight can catch these, with the result that repairs are often evident at the point where this upright joins the main beam.
Electronics
To get a true picture of how well the whole machine works it’s essential to couple it up to a tractor. Be aware most Liners can be set up to run their essential functions via a closed centre load-sensing hydraulic system to avoid using one spool valve set to constant pumping. However, if the tractor isn’t set up for this it is possible to switch from one mode of operation to the other by lifting the cover on the main beam that houses that main valve chest and twisting the labelled knurled knob.
There are various different control box options. Most Liners go out with the basic blister-pad panel with buttons and LEDs to toggle through all the main functions (icons making this fairly self-explanatory – transport/work mode, front rotor width, etc) and a pair of plus/minus buttons to tweak accordingly.
There is also the option of Claas’s black-and-white ‘Communicator’ display – about $2000 extra when new. As an alternative, all post-2014 machines have the ability to run through an ISObus controller.
Rotor position is monitored by potentiometers on the fold points. These tell the control box when they have reached their predetermined height for headland turns. If they’re required to lift higher to clear big-crop swaths it’s possible to do this by working the control panel buttons in a set sequence outlined in the manual.
With oil flowing to the valve chest, check that everything folds, lifts, and extends out as it should. While the electronics can play up, more often than not it’s dry telescopic beam wear pads and pivot pins that’ll be the sticking point.
Rotor height control
Hydraulic height control (HH) provides operators with the opportunity to tweak rotor height from the comfort of their armchair. If the rake in question is fitted with this option, check the sensors give the control box an accurate reading.
If it’s got manual height adjustment, check the winder handles run smoothly. Often under-use means they’ll get sticky or seize up.
A knotty issue
Anyone who’s spent much time behind the wheel of a forager will know the agony of following a single-rotor rake bundling one swath into another to try to build a decent row.
The usual result is a heavily-knotted rope of grass that brings the chopper to its knees. In some ways the four-rotor rake has the potential to create the same headaches if the material gathered by the leading tine arms is then swept into the swath again by the rear rotors.
Two manufacturers have come up with solutions to counter this issue. Kuhn uses hydraulic rotor drive to enable operators to tweak tine speeds to avoid the bundling effect. It also helps simplify the driveline – no need for a complex series of shafts to get power out to the rotors.
Pottinger takes a similar approach but uses conventional PTO drive to the rear cam tracks to provide a fixed RPM, and hydro motors over the front rotors to provide variable speeds.
What to pay?
Examples of four-rotor Claas Liners at dealers dotted around the country:
- 2002 Claas Liner 3000, 9.9-12m working width, good condition for age, £6500 (NZ$12,141).
- 2011 Claas Liner 3500, 9.9-12.5m working width, hydraulic rotor height control, 380/55-16 tyres, average condition – £16,950 (NZ$31,660).
