Machine Testing In The Presence Of ACRS

Thursday, 2nd July 2009
Are you struggling with the concepts involved when carrying out a machine test where ACRs are fitted?

The following are the key points to be considered:
  • Firstly, when we say "connect ACRs", what we really mean is activate the rams (go to auto phase). So when you first start the machine and connect all components the ACRs must be activated (in auto phase).
  • When the flow chart asks you to disconnect the cluster air admission and ACRs you are ringing the long milk tubes (to disconnect CAA) and de-activating the ACR rams using the sequence recommended. (This is dependent on the type of ACR being tested and is in your standards manual).
  • When you are asked to connect ACRs you are activating the rams using the recommended sequence i.e. go to auto phase. You are now testing the consumption of the rams in litres per minute. As soon as you have this figure you must immediately de-activate the rams again i.e. go back to manual phase again.
  • You must go back to manual phase because the next step is to un-ring the long milk tubes and test cluster air admission. If the ACR rams are still activated you will have no vacuum at the claw (checking if there is vacuum at the claw is a good way to confirm what phase the rams are in). Without vacuum at the claw you will not be able to measure any cluster air admission.
  • Just prior to doing the air flow at minus 2kPa readings (Reading 22) you must again activate the rams the machine is back in the same phase as it was right back at the start of the test. If you don't do this, you may well get a difference between readings 6b and 22 and 24b which are caused by you and not by the machine.
  • The only other thing you need to be aware of is that when you do the subtractions to get your air consumption figures you must make sure you are subtracting from the correct number i.e. subtract reading 19a from reading 17, not from reading 18, to get your first other vacuum operated components consumption figure.