Skip to content

How to purge air from the #9 Hydraulic Shank Assembly

How to purge air from the #9 Hydraulic Shank Assembly

Prevent premature wear and ensure correct shank breakout by purging air from your hydraulic system

Plough hydraulic systems require consistent hydraulic pressure to ensure the shanks break out at the correct pressure. Air can be introduced into the system through normal use and should be purged regularly. 

As air builds in the hydraulics, it causes the shanks to break out more frequently. It can also cause premature wear in the hydraulic cylinders and in some cases cause the end caps on the cylinders to break.

What machines is this for?

Agrowplow deep rippers with the #9 hydraulic shank, including the AP51, AP71, AP81, and AP91. 

The principals can also be applied to the #9 hybrid shank on the AP11 and AP31.

broken cylinder cap

When you should purge air from the hydraulics

Air should be purged from the hydraulics as part of your pre-season setup and as part of your daily pre-operational checks. If left in the system, it can cause the hydraulic cylinder caps to break.

If done regularly, this process should only take a few minutes prior to using the ripper.

How to identify air in the hydraulic system

Engage the tractor park brake and raise the shanks off the ground. Set the hydraulic pressure to 0psi. Apply steady pressure with your foot to the shank blade. A correctly primed hydraulic system will have very little travel. If you can break the shank back with just your weight alone, this indicates air in the hydraulic system. 

Check the hydraulic cylinder end caps. If the end caps are broken this also indicates air in the hydraulic system.push on the shank with your foot to see if it breaks back

Purging the hydraulic system of air


Ensure your tractor and plough are parked on flat, level ground such as turf with the tractor park brake engaged. Do not perform this operation on a hard surface such as concrete, as this will not provide enough surface for the plough blades to catch and gain sufficient leverage to break back while still supporting the weight of the frame.


  1. Fully raise the transport wheels into the upright position so the plough is resting entirely on the shanks.
  2. Set the tractor remotes to the neutral position.
  3. Slowly drive the tractor forward (less than 1km/hr) until the shanks are completely broken back and the plough frame is lowered to the ground.shanks broken back entirely and frame lowered to the ground
  4. Charge the plough hydraulic system by releasing the tractor park brake and setting the gear to neutral. This will allow oil to flow back into the plough hydraulics and slowly pull the tractor back as the frame rises and the shanks reset. 
  5. Watch the plough hydraulic pressure gauge to ensure the pressure remains until 1,000psi. Pressures above 2,000psi can make the oil and air mix together, causing a honeycombing effect. 
  6. Set the hydraulic pressure back to 0psi and manually check the shank breakout again as per the first point in how to identify air in the system. Repeat this process as many times as is needed to ensure the shanks don’t break back from manual pressure - usually 2-3 times is sufficient.
Previous article AP91 Machine Setup
Next article Agrowplow wheel nut torque chart
Can't find the info you need?

Can't find the info you need?

Call us on 1300 722 491 to speak to one of our friendly team who will be happy to assist you.

You can also view and download machine operator and parts manuals.