In this previous post on hydrostatic transmissions, I outlined the theory and technique for using case drain flow to determine the condition of a hydrostatic transmission pump and motor.

In response to this post, some readers thought that the function of the flushing valve warranted discussion, while others were still confused about the influence of the charge pump when … Read more

Hydraulic fluid straight from the drum, has a typical cleanliness level of ISO 4406 23/21/18.

A 25 GPM pump operating continuously in hydraulic oil at this cleanliness level will circulate 3,500 pounds of dirt, on an accumulative basis, to the hydraulic system’s components each year!

So to add hydraulic oil, and not the dirt, always filter new oil prior to … Read more

Since 2002 I’ve received a LOT of feedback from my newsletter and blog readers. One question that pops up regularly is: “Why do you give away so much valuable information in your newsletter and on your web sites?”

Well, I spent the better part of 27 years working in and running hydraulic repair shops i.e. rebuilding hydraulic components. During this … Read more