Constant pressure activated chain tensioning

When the machine is started the feed line (P) is pressurised. The pressure on the feed line have to be constant and should not range more than 0.5 MPa (7.25 Psi) from the pre-set pressure and should not cease until the machine is shut down. A reduced pressure from the pressure regulating valve (3) then acts on the pistons (1) and (2). ( ) The piston (1) keeps the chain tight while the pistons (2) hold the bar holder to the tensioning device when sawing is in process. The spring (4) delivers auxiliary tension during the first sawing operation after replacing the chain. The check valve (5) prevents the chain from becoming slack from external obstructions e.g. undergrowth

Fig. 15Constant pressure activated tensioning 1Piston 2Piston 3Pressure regulating valve 4Spring 5Check valve / alt. restrictor check valve