US Patent 7823653 Hand-held power tool with a belt tensioning device

A hand-held power tool for driving a working tool (1) includes a drive belt (3), first and second arms (5a, 5b) longitudinally displaceable relative to each other and carrying respective deflection rollers (6) of the drive belt (3), a belt tensioning device (4) located between the first and second arms (5a, 5b) and including a spring (8) preloaded against the first arm (5a), and a displaceable pressure piston (9) located between the spring (8) and the second arm (56).