Four-rotor rakes have a demanding workload when silage season kicks off, so getting your rake into shape beforehand will help prevent frustrating breakdowns when the pressure is on.
With the insatiable appetite of selfpropelled forage harvests growing and balers accepting more material at their pick-up reels, the four-rotor rake is the go-to choice for many contractors and farmers.
As such, keeping them in good order is vital to staying ahead of the hungry harvest equipment.
To get an expert run through of everything that needs to be checked and changed ahead of the silage season, we spoke to Krone UK’s Jamie Moreton, who used one of the company’s 16-plate Swardro 1400 Plus, with three hard seasons of use, as an example.
However, many of our maintenance points will also apply to other makes of machine, although always check the manual for settings and service intervals.
Mr Moreton suggests a ground up approach to maintenance and checks, as any problems with the ground engaging gear are likely to reverberate throughout the machine.
THE main grass engaging element of the rake, the tines, should be checked periodically for even wear and any signs of cracking.
Krone has recently redesigned its rakes’ tine retention system, using a bolt and cast clamp.
Older rakes may still have U-bolts holding the tines in place, but these suffered from cracking, so should be replaced with the cast clamp when the U-bolt does fail.
With the cast clamp, tines can be used for a longer period, as the clamp can be turned around, to exert more force on the spring of the tine, rather than replacing with new tines once the ‘springiness’ has been lost.
Bolts holding the tines on should be torqued to 95Nm (check manual for other makes).
As for the tine arms, these should be tight and only have a small amount of rotational movement when wiggled by hand.
Mr Moreton says there is little difference in wear between the front and rear rotors, even though the rear rotors do twice the amount of work, but these should be inspected for any uneven wear.
WITHIN the main rotor housing, the cam track lifts and rotates the tine arms which have roller bearings at the end.
Mr Moreton says typically these do not tend to throw up too many problems, provided they are kept topped up with liquid grease.
If a tine arm has been hit or bent, there could be some internal damage. However, two bolts holding the arm in place can be removed, along with the alloy cast housing.
If needs must, the rake can be run without a tine arm, but the cavity in which it once sat needs to be sealed to prevent debris getting in.
When replacing tine arm assemblies, it is important that the bolts holding them in place are torqued correctly, in this case to 105Nm, to prevent the alloy casting from cracking.
Mr Moreton says rakes are often run at too high an RPM, which results in grass being thrown on top of the rotor housing.
The grass then gets wedged in the top of the rotor housing and the main arm, causing the seals in the top of the rotor to wear.
While there is no low viscosity liquids which will escape, some seepage of the liquid grease can occur, and these seals should be replaced if there is any evidence of this.
MAINTENANCE starts at the castor wheels on the rotors, which Mr Moreton says are frequently overpressurised.
The manufacturer recommends running these at 1.5-1.8 bar, depending on the manufacture year, as at this pressure a small amount of suspension is afforded.
When over-pressurised, all bumps in the ground are transmitted through the machine, which can lead to structural issues in the chassis.
Castor wheels should also be checked for free and unhindered rotation. If they do not spin freely, two bearings inside the rim will need to be replaced, a quick and simple job.
Mr Moreton says if the rake has stood outside for a prolonged period of time, water ingress is usually to blame.
A generous application of grease in each of the pivot points on the castors will allow them to follow the ground effectively.
Rotor inclination is set individually for each tine by adjusting the height of the castor wheels.
The manufacturer says best results are obtained if the rotor inclination is set so that the tines are closer to ground level when depositing the crops than at the start when picking up the crops.
On a flat surface, unfold the rake and lift the rotors slightly off the ground, before adjusting the stop bolt on the top of the assembly.
The outer wheels should be adjusted to lift the rotor, ensuring no tines will make contact with the ground.
TO get the wide working widths and low transport height associated with four rotor rakes, the rotor arms not only fold up, but also telescope.
Plastic wear plates keep the telescopic mechanism straight.
These should be inspected regularly for excessive wear, which will see the tine arm start to droop if not prevented.
Mr Moreton says the arms should have a fine layer of grease on them, but not excessive amounts as this can turn to paste with dust in the air and cause quicker than normal wear.
Most of the pivoting parts involved with folding and infield operation have a 20-hour greasing interval. Shafts on the machine vary between 100 and 250 hours.
The main frame and running gear also need a good inspection for cracks and defects, paying particular attention to areas low down which could potentially ground out on undulating ground.
The working height of the example machine is controlled electronically. Mr Moreton says to get the best life expectancy out of the electric motors that wind working height up and down, when raising the working height, the rotor should be lifted off the ground.
This way, the motors are not having to lift the entire weight of the machine.
Otherwise, the motors are fairly robust he says, just requiring some grease on the screw mechanism. At the top of the rotor there is a linkage that should rest in the middle of its slot, to allow for a degree of contour following.
DUE to the size and complexity of the rake, a number of proximity sensors are located around the machine. These relay to the in-cab computer the status of various parts.
Mr Moreton says the sensors responsible for determining the location of the fold out arms can play up from time to time, especially if having encountered a gatepost or a rodent’s fancy.
The first point of call if they are throwing up issues is to identify the troublesome one through the computer and examine it.
The distance between the sensor and the steel it is measuring should be as the manufacturer recommends.
On this example, two types of sensor are used which should be set at 2mm and 5mm.
If the rotors have been hit, they will need straightening, checking for clearances against the frame, before adjusting the proximity sensors.
Sensors on the actuators also provide information to the computer on their extension level to prevent the rake from damaging itself. If these are working incorrectly these will also show up on the computer.
Electrical issues, while not common, can cause profanities to be shouted, and are often due to furry nuisances.
Ensuring the rake has been cleaned off at the end of the season and no grass remains on it will help to prevent their attraction to cables.
PROTECTION for the rotors is provided by ‘rattle’ clutches on the shafts, and should be replaced if not enough resistance is given when working, causing them to go off frequently.
Whole clutch assemblies can be provided by the manufacturer, or pins and springs can be purchased
from consumables companies.
Mr Moreton advises giving the clutch a single shot of grease at the start of the season, to prevent it slipping too easily.
A common feature among all big rakes is the number of gearboxes present, directing power in different directions.
This example has six, not including those on top of the rotors.
Each gearbox should be drained at the start of the season and the oil examined for contaminants. They should be refilled with SAE 90 oil (check manual).