Saw activated chain tensioning

When the feed line (P) is pressurised from the saw function, a reduced pressure from the pressure regulating valve (3) 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. 14Saw activated tensioning 1Piston 2Piston 3Pressure regulating valve 4Spring 5Check valve / alt. restrictor check valve