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A section of floor at Hope Valley College, Derbyshire, can now rise up to 600mm to create an elevated platform that can be raised and lowered for special events.

Hope Valley College is a small, rural, comprehensive school based in the Peak District National Park, Derbyshire, England.

Derbyshire County Council decided that a mechanically retractable platform would be of great benefit to the college for the performing arts students as it would encourage talented students nationally to enrol at the college.

The ability to have a raised platform would give the students the experience of performing on stage without compromising on the room’s flooring area for other classes.

The school commissioned Garrandale to design and produce the elevated platform, which in turn contracted Power Jacks to supply the lifting mechanism.

The engineering company decided to use screw jacks rather than hydraulics, as the electro-mechanical screw jack system was cleaner, easier to maintain, easier to synchronise and more reliable and more environmentally friendly.

Having worked with Power Jacks for many years, the company knew it could provide a worm-gear jacking system that would effectively raise and lower the elevated platform.

Power Jacks supplied Garrandale with E-Series screw jacks, gearboxes and drive shafts.

The E-Series screw jacks have an integrated forced grease-lubrication system, which pumps grease through the gear directly on to the flanks of the lead screw to ensure that the screw always has an optimum lubricant covering.

This also lowers friction and operating temperature while increasing life.

All drive shafts used were of the ‘self-supporting’ type for easy and cost-effective installation.

Using them meant the screw jacks and bevel gearboxes could be directly connected to the drive shafts without any intermediary couplings or plummer blocks to support conventional drive shafts.

The ultra compact gearboxes are designed for the transmission of rotary mechanical power through ninety degrees or split power from one input drive to two or three output drives.

They use precision-cut spiral bevel gears to deliver a smooth and quiet transmission with an efficiency of up to 98 per cent.

All are built into a robust gearbox housing optimised to minimise installation space, delivering high torque ratings and good thermal characteristics.

The useable platform measures approximately 4 x 4m and was designed to the specification supplied by Derbyshire County Council.

It lifts a uniformly distributed load of 5kN/m2 and it can raise this load to a height of 600mm from floor level.

The mechanical jacking system consists of 4 x 25kN screw jacks that are linked together by bevel gearboxes and drive shafts.

To allow the top surface to sit flush with the floor in the room, the platform jacking mechanism is installed into a pit.

The whole assembly is powered by a single 3kW motor that drives through an 8:1 reduction gearbox with the jacks supported on fabricated steel pedestals that are secured to the floor of the pit.

These pedestals are linked together in groups of two, providing support for the bevel gearboxes and drive motor/gearbox.

On top of this jacking system sits the main platform.

This platform is constructed from two off lengths of universal beam with lengths of square hollow section passing through holes cut in the web.

Each length of universal beam spans between two jacks at 90 degrees to the bevel gearbox supports.

An access hole is also fabricated into the platform structure to allow maintenance to take place.

The sides of the platform are constructed from hard plastic-faced chipboard and are attached to the steel work via folded steel bracketery.

The platform and butting up to the top of the side plates are brushed stainless-steel edging plates that are mounted to form a barrier for the wooden flooring to be butted up to.

Mounted to the edge of the pit and facing the stainless-steel plates are mild steel edging plates.

These form a barrier for the flooring to butt up to, external to the platform.

Two limit switches are employed to stop the platform at the top and bottom of its travel.

This limit switch arrangement is mounted to the bevel gearbox support frame near the lift’s motor/gearbox assembly.

In the down position, the platform top is flush with the floor in the room.

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