Most people who consider themselves to be mechanically inclined often struggle with the question of whether to tune up or trade in a disc mower-conditioner. For some it’s like admitting defeat to trade in.

Hay and Forage, Crop Preparation Marketing Manager / New Holland

Regardless of mechanical inclination, the reward for buying new is always updated model features, renewed warranty coverage and trouble-free operation.

With hay season just around the corner, it’s time to look at your disc mower-conditioner. Here are my guidelines for a pre-season inspection to help you answer the question if it’s time to trade in or tune up:

Age and general condition

Safety is of upmost importance: Damaged or missing guards and shields must be replaced before season. Inspect the machine’s power takeoff (PTO) shields, safety curtains and all other guards. Always replace any damaged sheet metal components. Touching up the paint is always a good idea.

Tires and wheels

Inspect tires and wheels and look for signs of uneven tread wear, dry rot deterioration, sidewall cuts and wheel damage. Repair or replace worn tires or parts before your machine leaves you flat. Check your operator’s manual for proper inflation pressures.


Beyond a quick visual inspection, start at the tractor drawbar and PTO connection, working back to the main drive gearbox followed by the cutting and conditioning components.

Inspect both the tractor’s drawbar and implement hitch for proper connection. A tractor’s drawbar is subject to wear, and condition can become a problem. If the draw-pin hole becomes elongated, the connection can become sloppy. Inspect the condition of the safety tow chain and if not factory-equipped, consider purchasing one.

For swivel-type hitches, check the gearbox oil level. If it has reached the service interval, drain and refill with the appropriate gear oil.

Check the PTO connection to the tractor’s output shaft. If it is loose, fits sloppy or if the coupling lock is not working, inspect yoke, tractor output stub shaft and coupling lock. Clean, repair or replace suspect parts.

Inspect all U-joint yokes and crosses for excessive play or damage and lubricate all possible joints. Vibration from a loose joint can damage the drive line and the tractor’s PTO system. Pay special attention to constant velocity joints. These assemblies have a double cross, a centering plate to guide the joint.

Slip and overrunning clutch assemblies are often part of a drive line protecting your implement and tractor’s PTO system. Grease the overrunning clutch as part of scheduled maintenance.

Prior to seasonal use, most manufacturers recommend slipping to ensure proper clutch function. Follow the instructions in the operator’s manual when inspecting your slip and overrunning clutches.

The disc cutterbar

Take a hard look at the condition of cutting discs, crop lifters and knives – but a detailed pre-season inspection should go further. Check the oil level in each disc drive module. If the service interval has been reached, drain and refill with the appropriate gear oil.

If your machine is a spur gear, common sump-style, check the volume as recommended in your operator’s manual. When replacing oil, pay special attention to the volume and type of oil. Overfilling or using the wrong oil type can result in overheating and damage.

With the tractor PTO disconnected, turn the end disc by hand in its normal rotation while looking down the bar. Each disc should begin to turn as lash is taken up. If one or more discs are slow to turn, or the lash is not taken up in a predictable way, a drive problem may be evident.

To help isolate a problem area, move down the bar, turning each disc in its normal rotation. Discs should turn freely and smoothly as you rotate them. If a problem is suspected, hold slight resistance on the adjacent discs while turning. If one disc suddenly turns or jumps, internal damage is evident.

Tip: If the disc is protected by a shear hub or coupling-style protection, inspect the hub to ensure it has not previously sheared.

Inspect each disc drive assembly by rocking discs up and down. Even with factory-set bearing pre-load, slight movement will be present. Excessive movement, or if a disc is “sloppy,” can be an indicator of a worn disc drive bearing or drive gear.

The roll conditioning system

Begin with a baseline inspection of rubber rolls for obvious condition issues caused by debris or improper adjustment. Rolls should be free of major defects so they can be properly adjusted.

Tip: A bent knife can contact and damage a roller on some models. Look for signs of cut damage and always replace damaged knives.

Look at the oil level of the drive gearbox; if it has reached the service interval, drain and refill with appropriate gear oil. This gearbox is typically driven by a belt connected to the main-drive gearbox. Inspect this belt, looking for signs of uneven wear, dry rot deterioration, cuts or damage. Properly tension the belt or replace if necessary.

Roll timing adjustment should be checked periodically to ensure the rolls are adjusted to within tolerance. A visual inspection is sufficient. Check that lugs center in the opposed valley. Commonly, an adjustable flange is provided on the drive to move one roll to center the lug and valley.

On chain-driven rollers, timing can be complicated by chain stretch and sprocket wear. Reference the operator’s manual or contact your dealer.

Tip: Inaccurately set roll timing can result in contact between the lugs, causing excessive wear and machine damage.

Tip: A credit card measures 2⅛ inches tall and makes a handy tool for inspecting the lugs.

If the gap is set too wide, conditioning may be ineffective and the crop may be slow to dry. Roll gap recommendations are determined by the crop mown.

Set the gap to the minimal clearance necessary to crush and crimp an individual crop stem. For alfalfa crops, this adjustment should be 1/16- to 1/8-inch. For other crops, reference your operator’s manual or contact your dealer.

Tip: Use a roll-pin punch as a feeler gauge between the lug and opposed valley to ensure proper gap setting.

Check at each end and in the center to ensure the rolls are parallel.

The most common adjustment, roll tension or pressure, should be adjusted to suit crop conditions at the time of harvest for optimum conditioning for fast drying and hay quality. Use more pressure for heavy early crops and progressively less with late-season yields.

The flail/tine conditioning system

Like the roll machines, start at the drive gearbox by checking oil level. If it has reached service interval, drain and refill with appropriate gear oil. These machines are almost exclusively driven by a drive belt. Inspect it, looking for uneven wear, dry rot deterioration, cuts or damage. Always ensure this belt is properly tensioned.

Bent or damaged flail tines can cause rotor imbalance and bearing failures. Inspect the individual flails/tines for wear and damage, then inspect the flail pivots and attaching hardware.

If the adjustment is made via hand crank, ensure the threads are free; if held by a clip or spring handle, ensure it is in good condition, ensuring the hood does not lower unexpectedly.

If tuning up is in your future, you now have a good list to provide your equipment dealer to get the best service and advice. However, if you conclude it’s time to trade in rather than tune up, you have a better idea of the condition of your trade.

If buying new, start by researching the latest models and features, then think carefully about how a new machine would fit your operation.

Consider taking advantage of a larger model or self-propelled machine. It’s important to remember when you up-size your mower-conditioner, up-sizing your supporting equipment such as tedders and hay rakes may also be necessary.  PD

PHOTO: With hay season just around the corner, it’s time to look at your disc mower-conditioner with hard, discerning eyes and determine whether a tune-up or trade-in is in your future. Photo courtesy of Jordan Milewski.

Jordan Milewski is a crop cutting marketing manager With New Holland. Email Jordan Milewski.