on video Sources of Piston Pump Case Drain Flow

 

The case drain line — it's a critical feature of piston pumps, allowing for lubrication of pistons and slipper pads, absorbing exhaust flow from the pump controller, and preventing the swash plate from moving over center. In this video, we take you through the different flow sources that end up in the case drain line, why they happen, and what you should do to maintain your case drain flow and prevent catastrophic failure.

One way to troubleshoot a final drive that seems weak is to take a look at the rate of flow from the case drain line. In this Shop Talk Blog post, we are going to review the purpose of a case drain line, look at what case drain flow can tell us about a final drive, and then discuss how to estimate the case drain flow. We'll finish up by looking at how to evaluate the case drain flow to determine if the problem is your final drive.

Purpose of Case Drain Flow

The case drain line drains internal leakage from the hydraulic motor back to the hydraulic tank. The case drain should experience minimal flow and low pressure. Keep in mind that there will always be some level of internal leakage expected. All piston-type hydraulic motors will leak hydraulic fluid from the rotator group. This is a good type of leak: it lubricates the piston shoes, the swash or thrust plate, and the area between the cylinder block and the valve plate.

 

The case drain line — it's a critical feature of piston pumps, allowing for lubrication of pistons and slipper pads, absorbing exhaust flow from the pump controller, and preventing the swash plate from moving over center. In this video, we take you through the different flow sources that end up in the case drain line, why they happen, and what you should do to maintain your case drain flow and prevent catastrophic failure.

One way to troubleshoot a final drive that seems weak is to take a look at the rate of flow from the case drain line. In this Shop Talk Blog post, we are going to review the purpose of a case drain line, look at what case drain flow can tell us about a final drive, and then discuss how to estimate the case drain flow. We'll finish up by looking at how to evaluate the case drain flow to determine if the problem is your final drive.

Purpose of Case Drain Flow

The case drain line drains internal leakage from the hydraulic motor back to the hydraulic tank. The case drain should experience minimal flow and low pressure. Keep in mind that there will always be some level of internal leakage expected. All piston-type hydraulic motors will leak hydraulic fluid from the rotator group. This is a good type of leak: it lubricates the piston shoes, the swash or thrust plate, and the area between the cylinder block and the valve plate.