![]() ![]() ![]() There are shear tests in both of these studies if interested in looking at them. The reason it will be explained in this post is because for lubing a bicycle chain with oil, it is important to know how viscous (i.e. It’s a measure of a fluid’s internal resistance to flow and shear under the force of gravity. Classification of viscosity for motor and gear oils was made by USA organization SAE (Society of Automotive Engineers) and SAE viscosity classification is often used for automotive lubricants. Viscosity index is a measure of how much the viscosity will change as temperature rises or falls. This can be explained due to higher disturbances from oil. However, the ISO Viscosity Grade (VG) is determined at 40C and will fluctuate depending on operating temperature. So you could have a 90 weight with a KV of 13.6, but it does have far to fall to shear out of range, so finding lubricant that falls in the middle or upper level of its range is beneficial in that if it does start to shear, hopefully it will not fall out of range and compromise protection. Let’s take a closer look: First, let’s talk about kinematic viscosity. Therefore, this study investigates the effect of varying oil viscosity in a gearbox transmission. These aren't recommended for use our bikes but just wanted to show the KV value.Įach oil on the market stating a specific grade has to have a KV for the ASTM D-445 test fall in these ranges, but the exact numbers can vary. We do have a straight grade 190 with a KV of 37.6. Here are the new viscosity requirements for the 4 grades stated in kinetic viscosity at 100*C, the ASTM D445 which is stated on all oils and gear lubes in cS(centistokes)Īs you look at these on the graph you can see that a 110 gear lube is almost the same range as a 50 weight oil.Īn example is our 20W-50 oil. What they did is take the 90 and the 140 and cut them in half to create the 110 and 190. It is a little dated as it does not have the 2 new gear lube viscosity grades that came out in 06, the 110 and the 190. Here is a viscosity chart I got of of BITOG. It makes them more recognizable, but their viscosities actually are very similar and do overlap. ![]() Gear lubes and motor oils are graded with different numbers only to try and avoid confustion between the two. Gearboxes do not have an oil pump, so the high viscosity. I've seen this discussion come up several times and thought I would just post this to show graphically how the grading systems for oils and gears are different.and similar. Manual gearboxes and differentials use rather highly viscous hypoid gear oils compared to engine oils. ![]()
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