Figure 2. Tribometer measurements taken at mile intervals on both sides of the track 1.1 Results


Based on earlier work there seems to be a consensus that on the [track] gauge face, a coefficient of friction value between 0.25 and 0.30 is desirable for rail friction mitigation. (Figures 3 and 4) present an example of the coefficient of friction readings for the reference mineral oil-based grease and the bio-based winter grease that was tested. The mineral oil-based grease was the reference grease and showed to carry for nearly five miles to the left of the lubricator. The bio-based grease too performed and showed a value between 0.25 and 0.30. This was the only winter grease testing performed due to time limitation. A reading of 0.65 coefficient of friction at the mile post 164 is an anomaly; even though both sides of the track showed the same result. Below mile post 163 was a rail yard which prevented further measurements. But, the results as presented here showed that both greases had carried to the mile post 172. The reference petroleum grease is currently the most commonly used grease by major railroads. The bio-based winter version of grease #3 shows performance similar in one direction and slightly better at the different direction from the lubricator location.


Figure 4. Tribometer measurements reported at mile intervals on both sides of the track for mineral oil-based grease on one track and bio-based grease on the second track (Cedar Rapids location OEM 2)


1.2 Conclusions


The summer versions of three bio-based greases were tested next to one mineral oil-based reference grease. Each test took approximately five weeks with one week time delay between each test to allow the residual grease from the old test to be consumed. Tribometer readings were taken every 7 to 10 days at one mile intervals both upstream and downstream from each lubricator site and on each side of the track. This means at each site four sets of readings were taken. One at the downstream side for one track receiving the bio-based grease; one at the upstream side for the same track receiving the bio-based grease. Then the measurement would be taken for the other track receiving the mineral oil-based grease both upstream and downstream side from the location of the lubricator. Since the mineral oil-based grease was the same for all four tests, at the beginning of each test the reservoir was topped off to the same level for each test. Ten 5-gallon pails of grease were put in each reservoir at the beginning of each test and the grease was leveled. The results show that in general bio-based greases performed equal or better than the reference mineral grease. The three bio-based greases were from three different suppliers two of which had indicated the bio-based grease was vegetable oil based. The nature of the base oil for the third bio-based grease is not known but the manufacturer markets the product as bio-based. The results coincide with the performance of those greases observed in the environmental chamber. The operators reported that the mineral oil-based grease is excessively tacky with tackiness that approaches the consistency of glue. By observation the grease shows a higher level of cohesiveness which could be helpful for pumping at colder temperatures. But, excessive cohesion comes at the cost of reduced adhesion which could reduce the distance the grease is carried down the track.


Figure 3. Tribometer measurements reported at mile intervals on both sides of the track for mineral oil-based grease on one track and bio-based grease on the second track (Cedar Falls location OEM 1)


The Cedar Rapids location using the two new lubricators from OEM 2 showed similar performance (Figure 4). On the right hand side of the chart from mile marker 101 only two measurements could be taken because of the location of a rail yard three miles from the lubricator. But, on the left hand of the lubricator, for six miles both mineral oil-based and bio-based grease carried with coefficient of friction between 0.20 and 0.30.


There are many performance variables that cannot be controlled in the field or in the equipment. The main conclusion that can be drawn from the data is that bio-based greases can pump and carry in the tested lubricators. Their extreme pressure property was superior to those of the petroleum greases as observed in the laboratory test results. The following section (to be published in the April 2016 edition of Lube Magazine) covers the environmental aspects of the test greases.


LINK www.elmuse.com


LUBE MAGAZINE NO.131 FEBRUARY 2016


43


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65