Disc mowers can be found on the majority of Irish farms nowadays. Like most machines, making contact with the surface, maintenance and setup is critical to ensure a long service life. A well-maintained mower could be the difference in a hassle-free season or one spent carrying out last-minute repairs at the worst possible times.

Here we offer some tips on the key areas to consider when it comes to maintaining a disc mower. Although we concentrate mainly on a trailed Kverneland mower for the purpose of this article, most of the advice applies to all brands of mowers, trailed or mounted. As with all maintenance procedures, safety should be paramount.

As always, when it comes to maintaining a machine, the saying “service it well and it shall serve you well” stands to reason.

1 Inspection

First off, check the mower over for any visible signs of oil leaks while dry. You may spot a small bit of weeping where oil might have started leaking over the winter. It is important to sort these leaks before any oil is replaced.

Clean the mower down to remove any rough dirt or debris, paying particular attention to the cutting bed. A dirty machine is obviously going to leave servicing a harder task and increase the possibility of a potential problem going unnoticed. Once clean and dry, inspect the mower again, checking closely for any leaks or structural cracks. Not only should the mower bed be inspected but the frame and suspension system should too.

Check over the slip clutch. Make sure it hasn’t seized over winter, and that it can be taken apart. Make sure the individual discs are not stuck to the steel. While they can be sanded down and cleaned, replacement is advised if they appear black or burnt.

The mower should be visually checked over for leaks, cracks or damage.

2 Driveline and gearboxes

Check the condition of the PTO and drive shafts. All crosses or universal joints should be free-moving and receiving grease. Covers and safety chains should be present and in place.

Gearbox oil quality and level should be checked. Milky white-coloured oil indicates the presence of water. If present, further investigation is required to find the root cause so that it can be rectified.

Belts where fitted need to be checked and correctly tensioned. Pulley bearings should also be checked for play.

It is worthwhile carrying a spare set of belts as it is likely they will be needed at some point.

Belt condition and tension needs to be checked.

3 Mower bed

When it comes to the bed, check the oil level and for the presence of filings. If any of the oil levels are low before replacement, you need to find out why and check for possible leaks.

Once oil levels are OK, run the mower for a short period, listen carefully from a distance for any unwanted sounds that might need further investigation. If there are no filings present and the oil looks in need of replacing, then do so.

Drain and refill as normal using the recommended oil. Each mower and brand will vary but a typical 10ft Kverneland trained mower bed will hold 4.1l of oil and a 9ft Kverneland mower with 3.6l of oil. An oil commonly used is GL75-90 gear oil, but consult with your dealer if unsure.

However, if there is a small amount of grit or filings in the oil, flush out the bed. This involves refilling with an oil and diesel mixture and running it for a few minutes to loosen up any grit.

It should easily flow out of the sump better than synthetic oil. In the unfortunate event that there are excessive filings or grit within the bed, it will need to be stripped down and power-washed.

Grit is usually an indication of trouble with bearings.

It is very important not to overfill the mower bed with oil. The bed has no breather like a gearbox has. If you overfill the bed it will cause excessive heat.

The oil level in the mower bed varies greatly from brand to brand so always refer to the operator’s manual or local dealer before starting this task. The oil change intervals for the cutting bed also vary from brand to brand.

Oil in the bed should be drained while warm, checking closely for metal filings.

4 All hubs, discs and stone guards

The hubs should be checked for excessive play. A rocking in the hub will indicate bearing trouble. If excessively worn they should be changed, otherwise they will only fall off in time.

The discs should be checked to ensure they are not excessively damaged or have chunks missing off them. They can be exposed to rock damage and wear so it is important to check them regularly. Damaged discs may cause a vibration in the mower. Running a mower at such speed with vibrations will lead to further damage. Ensure the top hats are securely bolted on. Mowers fitted with keyway or shear pin discs should be examined. Rotate or replace damaged, worn or bent blades as necessary.

The stone guards/skids on the underside of the mower bed should also be examined for wear and replaced if needs be. The middle section is very important as it also protects the bed, especially in the case of a blade bending backwards.

Finally, check over the bolts on the hangers that hold the bed on to the mower frame. It is held using five bolts each side. Check that the bolts are in good condition and are tight.

Worn or damaged blades should be replaced.

5 Conditioner and grouper

Firstly, check the condition of the two rotor bearings. More often than not, you will find wire caught around these bearings. If the seal is damaged it is a tell-tale sign the bearing needs to be replaced. Also, if any rocking or play is evident, they will need to be changed. It is not uncommon for these to fail over time, especially if not frequently greased.

Make sure all the tines are present on the conditioner and none are bent or damaged, checking for damaged or cracked hangers. If any hangers or tines are missing it will cause the rotor to run off balance and create unwanted vibrations. Check the state of conditioner belts. If the belts are any way hardened or cracked, replace them. Otherwise, they won’t last very long when the pressure comes on.

Where fitted, groupers should be checked ensuring full functionality and that all control box operated features such as variable belt speed, manual and automatic engagement/disengagement are working.

If fitted, the grouper should be checked over ensuring full functionality and no oil leaks.

6 Bed adjustment for a clean cut

Trailed Kverneland mowers have a mower bed height adjuster. Check the height adjuster for thread wear. Sometimes, the roll pin in the threaded bar can also break, meaning the bar will freely thread up and down but the cutting angle won’t change. Double-check the tension on the main springs. The tension should be set in the field and the mower should be able to follow undulating ground. Different operators will have varied preferred cutting heights. With mounted mowers, cutting height tends to be adjusted through bed pressure and toplink length. Correctly set drop arm lengths are important too to ensure the mower bed is running level.

Check the height adjuster for thread wear.

7 General

Tyre condition on trailed mowers should be assessed and the correct pressures set and equal in both tyres. The rams, hydraulic hoses and fittings should be checked over for leaks, corrosion and damage. Likewise, the lights should be checked regularly, especially side marker lights so other road users can easily grasp the overall width of the mower on the road.

Side-mounted mowers should have a functional transport locking system to ensure the bed does not lower unexpectedly. Where fitted, the break back protection mechanism on mounted machines should be correctly adjusted.

Regardless of the acres cut, a close eye should be kept on the mower throughout the season and working day, checking blade condition, potential mechanical issues, and keeping shafts and bearings well-greased.

Tyres should be in good condition and evenly inflated.