I presume you mean brake, can't think why a client would want this information and I have never come across this before. Are these dumpers your own vehicles or hired in from a plant supplier. If the latter, a thorough examination and test certificate should suffice. The only other form of check might be by the operator for daily/weekly checks which should be recorded. I suggest you contact the plant supplier and ask them whether they carry out three monthly brake checks...I doubt it. Then you know where you stand and can advise the client accordingly.

Dan, have worked on sites previously where regular brake checks are carried out but due to quarry regulations being implemented for certain areas of site. Could be related to this Regards Gerry

Check out the Guidance on Brake Testing for Rubber-tyred Vehicles Operating in Quarries, Open Cast Coal Sites and Mines http://www.hse.gov.uk/quarries/braketesting.pdf pg 14 refers to frequency of brake checks

Only required for Articulated dump trucks