Linear guides make wheelchair access possible

Edited by the Engineeringtalk editorial team Jan 15, 2001

A West Midlands supplier of specialist telescopic ramps, that give wheelchair users easy access to buses, has chosen the SBC Linear Guide from Unimatic for its latest generation of ramps

A West Midlands supplier of specialist telescopic ramps, that give wheelchair users easy access to buses, has chosen the recently launched SBC Linear Guide from Unimatic for its latest generation of ramps.

After exhaustive tests, the company, Passenger Lift Services (PLS) of Birmingham, decided to discard the previously designed-in linear guide and replace it with the Unimatic SBC.

�Not only did it work better and was more reliable, it also cost a lot less,� comments PLS Development Engineer, Adam Beck.

London-based Unimatic introduced a new range of linear bearings earlier this year, with the promise of outstanding quality giving total interchangeability and a policy of low pricing backed up by a Ono-risk� trial, on a sale or return basis.

PLS were sufficiently impressed with Unimatic�s confidence to take a closer look at the SBC Linear Motion System for their range of motorised ramps.

�The Unimatic linear bearings cost 25% less, and looked much better quality,� says Adam Beck, �and our tests bore this out.

The Unimatic guide was more compact, with more sturdy construction (using metal rather than plastic to hold the ball-race for example) and had a superior 300 kg load rating.

What�s more, the supply was much better.

For example, we wanted chamfered edges and the product arrived exactly as ordered.

Our experience with Unimatic has been excellent.� The market for wheelchair ramps for buses is rapidly growing, fuelled by legislation that has stated that, from 1st January 2001, all new public transport vehicles must have manual or powered ramps.

Dave Phipps, a director at PLS, explains, �We expect that rural buses will opt for the manual system, where the driver has to get out of his seat to lower the ramp.

However, in urban areas, the powered ramps, remotely operated by the driver, will be the choice to save time and this has been confirmed since this has been specified by London Transport.� The overall market is considerable, since all of the estimated base of 33,000 urban buses in the UK must be retrofitted by 2015.

To date, more than 100 systems have been supplied by PLS.

�We have produced a universal telescopic cassette ramp design,� says Adam Beck, �in just two width fittings and this is suitable for most of the buses in the British fleet � Volvos, Scania, Leyland, Daf, Mercedes and so on.

Unlike our competitors, we use an electric pump and hydraulics, which we find to be more reliable than going down the pneumatic route.

Two small cylinders push the ramp from its storage position and a third ram pushes the ramp down the Unimatic linear guide.

This design, which is awaiting patent approval, allows a 7� slope from the 250mm high bus floor down to the road, or a 4.5� slope to a 100mm high kerb.

The ramp is supported on one side by the linear guide and by roller followers on the other.� Because of the corrosive effects of grit, mud, water and salt thrown up from the road, PLS specified that the 640mm long guide and its two carriages should be Armoloy-coated.

A special chamfer is required to enable easy-mounting of the carriages and stainless steel balls, seals and scrappers are also provided.

Although most of these features are non-standard, Unimatic was able to demonstrate its ability to provide a product that is tailor-made to the application.

�Unimatic even guaranteed that the mounting hole configuration would be the same as from our previous supplier so that we did not have to do any redesign work,� concludes Adam Beck.

�We had no trouble retrofitting Unimatic�s guides and it meant that we had no additional design and manufacturing costs from switching suppliers.� PLS has, for many years, supplied bespoke systems for the welfare market, supplying wheelchair lifts for vehicles from Transit vans to commercial coaches, typically via local authorities for community transport and Odial-a-ride� services.

Now, with its new telescopic bus ramp, that is quickly and easily retrofitted to most bus types, PLS is confident of a major market share in this growing market.

Using the Unimatic SBC Linear Guide, with its benefits of long life, low maintenance and superior load carrying, PLS can offer its customers a better product at a competitive price.