The hydraulic pit clamp STU 1000 has been designed to solve the complicated and long pro cess for the assembling of the chair without using the wooden template reducing the working cycles. This feature makes the machine extremely flexible. The locking operation has been performed by two frontal cylinders and two lateral cylinder (one per side). Each cylinder has a rubber roller which guides the chair elements along all the clamping process without template. The positioning plane, adjustable by lifting mo-tor and 15° tilted, allows loading, unloading and setting up operations in a position ergonomically correct for the operator.