IDROTEC Ltd. designs and manufactures logging grapple . The IDROTEC calipers are all built and only in WELDOX , high index of elasticity and steel , on larger models , mounting two connecting rods to ensure optimum stability ; the bushes are self-lubricating BRAL ( bronze – aluminum ) , so as not to require continuous greasing in order to reduce maintenance to a minimum . They have been designed and tested to withstand heavy loads . All components are machined from CNC computerized machine tools to allow total un’intercambialità Parts replace if necessary . The cylinders of the various models are all large and entirely of steel to withstand the most severe operating conditions and also capable of withstanding operating pressures sometimes exceeding 250 MPa declared , placing of additional large margin . All the clamps are also equipped with a lock valve to ensure safe operation .