Why do the Original Equipment Manufacturers include relief on all reels?


Expectations and pressure to raise the over-all aesthetic quality of golf courses for members and players has increased tremendously over the past few years. This makes the Superintendent and Technician's jobs tougher than ever.

In response to these increased expectations, equipment manufacturers have developed new and better designs of cutting units that include changes in the metallurgy of the cutting components, increased cutting unit RPMs, changes in geometry, and changes in the overall reel construction. They've also experimented with varying degrees of relief, amounts of land areas on the reels, bedknife angles and attitudes, and more. The end goal has been to produce reels that provide the highest quality of cut for the longest period of time before requiring maintenance, and to that end, all reels include a relief on the blades.

Here are just two areas that were addressed and some reasons for each to be considered:

What role does relief play in Reel Adjustment?

In Depth Look

A horsepower study by John Deere was conducted several years ago. The bottom line result was if you “spin-grind only”, your equipment will run - at a MINIMUM - with 16% more stress on the working systems, 100% of the time. While 16% more stress holds true when setting with a wider gap that ensures no operational contact, look at the more significant role the OEM design plays if contact is made during the cutting process. See figures below.

.002” to .005” GAP OEM Relief 0.75 hp per cutting unit
(ensures no operational contact) No Relief 0.87 hp per cutting unit
No Relief
0.88 hp per cutting unit
2.59 hp per cutting unit

Note that a “reliefed” reel with contact requires little more horsepower than a “non-reliefed” reel with no contact.

Realistically, the traction system is designed to run with the additional load of added horsepower once the relief has diminished. It will cut and it will work okay, but it is not designed to run with this load on a regular basis. This is why re-conditioning the reel to “like new” will maximize performance and minimize potential issues.

We encourage you to take the minor amount of extra time to perform a complete grind job and include the relief. While it used to be labor-intensive, this process is now made especially efficient with the “hands-free auto-index” systems of the Accu-series.

Without question, relief grinding will minimize stress on the engine, reel and traction hydraulic systems. When looking at the big picture of scheduled maintenance, most facilities are not in a race to make their $15k to $45k investment to cut grass, and most customers agree that quality control of a premium grind will over-ride certain degrees of speed. Proper maintenance schedules and new grinder technologies create cost savings when you make the time to correctly grind the reels.

What role does relief play in the practice of Backlapping?

The relief grind plays a major role in whether the backlapping process is an effective tool to improve your cut quality. This is because the relief area on the reel blade provides a landing area for the lapping compound to adhere to. This enables the grit to be suspended on the reliefed area where it is then pushed and forced to pass between the reel and the bedknife, thus “effectively” removing metal. (See illustration to the right.)

On a flat ground or worn reel, the compound adheres to the back of the blade so when the reel rotates backward, there is very little grit that gets pushed between the two parts. Secondly, there is so much surface area and metal to remove on the reel blade that it makes the lapping process ineffective and time consuming. (See illustration to the right.) The thinner the land area, the quicker the lap time and the more effective the lapping process.

Some people extol the negative ramifications of backlapping primarily because relief is needed on the reels to be effective. This has encouraged misleading claims, but the fact is that backlapping can be an effective tool for maintaining high quality of cut standards, but must be conducted as intended.

In Depth Look

◄Previous Next►