Roller Testing: Expensive Isn't Always Best

Developing a comparative test for rollers has been a goal at AgParts for many years. Testing programs for rollers have been developed by harvester manufacturers such as Lockwood and Pik-Rite. These companies were primarily interested in evaluating the wear life of digger chain, both hook chain and belted chain. Their tests were designed mostly to test the life of chain and roller testing was incidental.

At AgParts, we are primarily concerned with roller life under actual field working conditions. It is quite difficult, if not impossible, to devise a test that perfectly correlates roller wear on the test stand to wear in the field. Our test stand is an attempt to determine how long a roller will last on a typical harvester under actual field conditions. We run the rollers against a drum which has welded 7/16 diameter steel rods on the periphery. This creates a bouncing force against the roller which simulates conditions in the field. The drum is enclosed in a hopper into which we dump about 100 lbs. of blow sand, alternately wet and dry. The rollers are mounted on arms of different weights. We have a 30 lb. arm, two 80 lb. arms and one 120 lb. arm. The weight is the actual force of the roller against the drum. The 120 lb. load is assumed to be typical of a roller at the turn around point on a digger chain. The 30 lb. arm is more typical for a roller in a carrier position, either on top, carrying the load up the conveyor, or in a carry-back position.

Roller Tester Setup

We have run tests on about 50 rollers between July and October, 1998. It appears that any roller which runs 600 hours (4 weeks at 24 hrs./day, 7 days/week) on our test stand will last at least 10 years on the average harvester, so long as it is able to turn freely. Naturally, if a roller is jammed by rocks or mud, the life expectancy will be drastically reduced.

We are not ready to publish full results of these tests yet, but we hope to have data available by early 1999. We have already had some surprises. Our own 4 and 5 inch rollers made from used truck tires, which we thought were fantastically good, have not done too well on our test stand. The most spectacular roller failure to date was a Grimme roller costing $75.00. We bought two of them from a local dealer thinking that the high cost would translate to long life. We were amazed when they failed at 270 and 400 hours. This test proves that the most expensive is not always the best.