Along the subframe are protective rubber blocks positioned. These are made from EPDM material and help to carry the load and protect against metal to metal wear. The front most pair is under extra high forces and made from UHMW material instead.
Inspect the protective rubber between the subframe and the tipper body on a weekly basis. If the rubber is compressed so that the upper surface is in line with the attachment plates the rubber needs to be replaced. Also if the rubber is cracked or in other ways damaged so it loses its ability to absorb compression and regain its original shape, it need replacing. All bolts needs to be in place to hold the rubber firmly. Tightening torque should be 25Nm.