Proper air-bleeding is a critical step in installation and use of hydraulic cylinders. This article will explain how to bleed telescoping(multi-stage) cylinders and the parts required.
bleeder location
The location of the bleed port will vary depending on the type of cylinder.
Standard Cylinders
Standard Airoflex cylinders will have the bleed port on on the smallest sleeve (near the top pin of the telescoping end) at the a-frame of dumper connection.
Inverted Cylinders
Inverted cylinders, typically used on smaller trailer tippers or portables tippers will have the bleed port on the top of the cylinder (furthest away from the telescoping end) next to the lifting eye.
PORT VARIATIONS (TELESCOPING CYLINDERS)
- Airoflex standard telescoping cylinders
- Size: 1/8" NPT Port
- Inverted Cylinders
- Cylinder Model 911001 (portable tippers, some trailer tippers)
- Size: Varies (adapter available for all port sizes)
- Bleed Port Adapter Part #: 903036
- Size: Varies (adapter available for all port sizes)
- Cylinder Model 911003 (2025 and newer)
- Size: 1/8" NPT Port
- Cylinder Model 911001 (portable tippers, some trailer tippers)
required parts
Bleed Adapter - Part #: 903036
The bleed adapter attached directly to the bleed port on older inverted cylinders (model # 911001). This part should be removed after cylinder is bled.
Bleed Valve - Part #: 903016
The bleed adapter attached directly to the bleed port on older inverted cylinders (model # 911001). This part should be removed after cylinder is bled.
Bleed Hose - Part #: 905023
The bleed hose connects to the bleed valve. The hose is used to direct oil to a bucket or other containment while the cylinder is being bled. The hose should be removed after the cylinder is bled. Longer versions are available.
CYLINDER BLEEDING PROCEDURE
- Start pump motor(s) and allow the power unit to idle for 10 - 15 minutes.
- Bump the controls for each circuit to check for proper response / operation.
- Bleed any auxillary line circuits (back-stops or pit doors) first. These are typically dual acting cylinders. Ensure all auxillary lines are bled and operating correctly before bleeding the telescoping cylinders.
- Remove the bleed port plug from the cylinder.
- Install the bleed adapters if applicable (part #903036). Warning: Do NOT overtighted the bleed adapters as the male threaded end can break off in the cylinder port.
- Install bleed valve (Part # 903016) and the bleed hose (part # 905023).
- Note: Longer versions or extensions of the bleed hose are available.
- Place the bleed hose so the oil drains into a clean bucket or other storage container
- Actuate the cylinder control and continue until out-flowing oil is free of air bubbles.
- Remove the bleed hose, bleed port and bled apadater (if app.) and replace the port plug.
- Operate the cylinders through a full range of motion.
- Cylinders may need to be bled multiple times over several days until all the excess air in the system has been removed.
- Note: Ensure the tank oil level is maintained after bleeding. Only clean oil should be put back into the power unit reservoir and it should be run through a filter prior to being added to the reservoir.