A key part of inserters made by Schur Packaging Systems is an assembly of four star shaped wheels which insert enclosures into folded newspapers. The assembly is held together with ETP-Express locking bushes which are fastened with a single radial screw. The ETP bush allows a compact assembly as no axial access is needed. A high accuracy of run out is achieved which is important for balance and high speed running. Also the single-screw fixing means that it is easy for the assembler to achieve precise orientation of the wheels.
ETP-Express is a hydromechanical locking bush which connects hubs to shafts without the need for keyways or collars. A single radially mounted screw pressurises an internal chamber causing the inner and outer walls to expand, thus creating a backlash-free connection between hub and shaft. The Express bushes are available for shafts from 15 to 80mm, and also in stainless steel construction for shafts 15 to 60mm.
On the Schur inserter, the ETP-Express bushes achieved run out values better than 0.02mm leading to vibration free running at speed. Setting and positioning is easily done by hand, with a tightening torque of only 5Nm applied by Allen key. Thin walled hub construction and alloy materials are possible as the bush exerts a low surface pressure of about 70N/mm².