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Can someone explain the mechanics of my bobcat chain case and filter?

clydesdale6 ยท 2020-10-01 23:36

I have a bobcat s150 skid steer with 910 hours and I am getting ready to change the hydraulic fluid. While looking through a service manual, I discovered that there are two "case drain" filters. Are these filter for the "chain case"? I understand that there are chains on each side to power the wheels. When they say "case drain" is this short for "chain case drain"? Is there one filter on the left and right side pump? Thanks.

Replies9
  1. #1BigWrench552020-10-02 00:52

    The short answer is no. The hydraulic motors for the chain drive have slight internal leakage inside the case. And that is drained back to the hydraulic tank. That is the case drain. The filters are there to catch debris if there is a failure in one of the motors and preventing the rest of the hydraulic system from being contaminated. Also some hydraulic pumps have case drain as well.

  2. #2clydesdale62020-10-02 08:30

    Thank you for that explanation.

  3. #3clydesdale62020-10-14 22:23

    OK, I could use a little more clarification with regards to the chain case oil vs hydrostatic system oil. To change the chain case oil it looks like I remove the plug in the center of the front of the machine and pump it out and then pump in new fluid. I do not believe there are an filters for the chain case. Is that correct? What is in the chain case? Just the chains and sprockets bathing in this massive amount of oil? The hydrostatic fluid is then in the reservoir and the two drive pumps and 4 wheel motors? Or have I completely misunderstood this? I want to replace the oil in both systems. I have all the filters for the hydrostatic system, but there does not appear to be any filters for the chain case itself.

  4. #4walkerv2020-10-15 00:31

    Yes the chain case is just a big tub of oil no filters or pumps in it just chains shafts and sprockets.

  5. #5clydesdale62020-10-15 22:35

    Great. Thank you.

  6. #6clydesdale62020-10-21 22:21

    Ok, I have another follow up question. So, when they say a "case drain filter" , what "case" are we taking about. The wheel pump case? Thanks.

  7. #7mitch5042020-10-21 22:59

    It filters internal leakage in your hydraulic motors as it goes back to the tank

  8. #8mitch5042020-10-21 23:03

    It filters internal leakage in your hydraulic motors as it goes back to the tank

  9. #9clydesdale62020-10-21 23:04

    Thanks. Is there only one motor for each side? That motor drives sprockets and chains for each side? I thought there were 4 individual wheel motors. Thanks for the education and clarification.