Power Transmission
Fig. 4. Power Jacks’ compact cubic C-Series screw jack is available in around 140 million standard configurations by virtue of its modular design.
Most screw jacks are connected either directly or indirectly to a motor, but Inkoma has developed an innovative model that eliminates both the separate motor and the internal gearing. Its DSH screw jacks feature a special torque motor that drives the ball screw spindle directly, resulting in smooth, backlash- free motion with virtually no mechanical losses and high energy efficiency. Specially selected bearings ensure the spindle can withstand both tensile and compressive loads, and the unit is suitable for highly dynamic applications; seven cycles per second and a maximum linear speed of 32 m/min are quoted, with 100 per cent duty cycles possible. Repeatable positioning accuracy is also claimed to be very high.
Multiple DSH units can be synchronised, with the torque motors used to control the speed and position of the ball screw spindles, and integrated brakes are available for increased safety. Inkoma offers both rotating-spindle and rotating-nut designs in five sizes, with a maximum lifting force of 1000 kN. Compared with conventional screw jacks, the DSH units are claimed to offer simplified machine construction, easier installation with mounting in any position, and lower maintenance. Each application has to be considered on its own merits,
but screw jacks - and the Inkoma DSH alternative - are undoubtedly versatile. Provided they are specified correctly, screw jacks can be robust, reliable and cost-effective. l
140 million standard configurations T
owards the end of 2010 Power Jacks launched the compact cubic C-Series screw jack that is available in around 140 million standard configurations (Fig. 4). The C-Series complements the company’s existing high- performance S-Series cubic screw jack and is said to deliver new application versatility. Bruce Hamper, Power Jacks’
customer service and marketing director, says: “The C-Series is our response to an identified market need for a screw jack possessing its very specific qualities and characteristics. “It represents the latest stage in
the evolution of our product range, based as it is upon the principles of
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our classic E-Series screw jack that is long established and proven in the market. “We have adapted those principles into this new C-Series cubic design, which we believe offers exciting new market opportunities. “The C-Series is durable and
adaptable and boasts a modern, sharp design. One of its key assets is the versatility it offers in terms of mounting methods, reflecting our commitment to offering customers the widest possible range of options. It is ideally placed to serve a host of industrial applications, operating individually or as part of a multi- unit jacking system.” Special features of the C-Series jacks include two screw lead options
and two gear ratio options for each screw jack size, an aluminium- bronze worm gear, and lubrication via two integrated systems. The gearbox housing is made
of either highly durable spheroidal graphite (SG) iron or aluminium, providing a robust unit that firmly and accurately holds the gear set in a reservoir of lubricant. The worm gear set is of a proven
design commonly used across Power Jacks’ portfolio of screw jacks, and there is forced grease lubrication of the lead screw. Standard C-Series units are complemented by anti- backlash, anti-rotation and safety nut versions, and they are available in four standard capacities from 10 kN to 100 kN. l
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