The HSMK hydraulic clamp is a machine that makes final assembly (full clamping) of a firstly tenoned chair frame.

The frame is made as a welded construction from steel sections. Inside of it is a clamping chamber, into which the tenoned chair frame is place for assembly. Three units of hydraulic actuators are attached to the machine frame (two- or three- sided chair clamping) and the amount of actuators in a unit depends on chair construction. In the back part of the clamp behind the clamping chamber, a hydraulic drive unit can be found. The clamp loading chamber consists of three mutually perpendicular planes serving as bases for the assembled chair. Setting stepless pressure regulation gives the capability of attaining the variable clamping force necessary for correct chair assembly. In order to avoid the risk of damaging the chair while it is being assembled, the pressing chamber is lined with plastic, and the hydraulic actuator holders with felt.
The machine can be modified depending on the chair construction.