The reel bearings are responsible for supporting the reel and keeping it perfectly cylindrical in the frame when it is rotating.
If these bearings are worn and have movement, they will no longer support the reel centrally and will allow it to oscillate, which will constantly vary the distance between each individual reel blade and the bedknife.
This then leads to not only an inconsistent and poor quality of cut, but also gives a poor finish when we grind the reel, as the distance between the reel blades and the grinding stone will also vary, leading to blades being ground to different lengths.
The condition of the roller bearings is also critical due to the height of cut being solely controlled by the positioning of the rollers. If the roller bearings have any movement in them at all, this will constantly change the height of cut as the unit travels across the turf.
A small amount of movement may not seem a problem, but now I'm seeing greensmowers regularly set to heights of 3mm and under, and just one millimetre of movement in a roller at these heights will almost certainly cause units to scalp and damage precious turf.
When lubricating cutting units, it is critical that the correct grease is used at the correct intervals. The manufacturers will have selected a grease that meets all the requirements relative to the speed, loading and temperature at which the bearing runs. The intervals will also be the result of extensive testing of the units in varying conditions. This information will be readily available in the operators' manuals.
Correct lubrication of bearings is essential, but more critical is the condition of the bearing seals. Cutting units work in the worst possible conditions for a bearing to be running, a cocktail of sand from topdressing and water, often injected from the pressure washer! The seals are designed to keep the cocktail out and the grease in. Any damaged or missing seals should be replaced. If they are not, bearing damage will follow closely behind.
Over greasing a cutting unit can cause just as many problems as under greasing. If too much grease is pumped into a bearing, the pressure can cause a seal to pop. When this happens, the seal is almost certainly going to be damaged.This then allows the sand and water into the bearing, causing wear and damage.
Another result of over greasing can be excessive grease leaking from the seals and then dropping off onto the turf. This causes an unsightly mess, as the grease is almost guaranteed to fall into the path of a roller on the cutting unit and then be smeared all over the 18th green!
This is then impossible to remove and, as grease is extremely water resistant, takes forever to fade away. Bio-degradable grease is available, but always check it meets manufacturers specifications. A far simpler solution is to ensure excess grease is cleaned off before the machine goes out!