November 2011
Flexible shaft couplings are adaptable and economic
Curved jaw couplings for shafts 5 to 90mm
Techdrives offer a highly adaptable range of curved jaw shaft couplings with rated torques from 11 to 1465Nm. Curved jaw couplings consist of two cast or machined hubs that connect through an elastomeric element. The contact faces are curved to spread the load which avoids stress concentrations and prolongs service life. Such couplings are simple and economic solutions for the connection of two shafts, accepting moderate angular, radial and axial misalignments in a compact size. Standard dimensions have become established across Europe and components can often be exchanged from one manufacturer to another.
Techdrives offers three models with increasing specification. The standard type GR is a general purpose coupling for shafts from 5 to 90mm. Hubs are cast aluminium or iron with unmachined jaws which keeps cost low but does introduce a little backlash. All the backlash is taken out with the next model, the GESM, with machined jaws and aluminium clamp hubs which connect to shafts from 4 to 80mm without keyways. A further higher specification model, the GESA, uses shrink disc technology to increase the rating of the friction connection between the hubs and shaft, typically by a factor of 2.5.
All three models have a choice of four grades of elastomeric elements that change the coupling characteristics. They are identified by colour – yellow and blue elements are made from softer polyurethane and give lower torque ratings but accept higher misalignments. Red and green elements have higher torque ratings and torsional stiffness. All the elements are dimensionally identical and have similar ratings for ambient temperatures, around -30 to +90ºC. Therefore customers have the chance to optimise the shaft coupling for torque, stiffness and misalignment.
A number of options are available for niche applications such as ATEX ratings, flange to shaft connection, spacer couplings and larger sizes to 6650Nm. Availability is good with deliveries of a few days for common models up to 4 weeks for more unusual designs. The Techdrives curved jaw couplings offer an excellent balance of performance and economy for general purposes up to precision handling.
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