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Home blown success

A new hand held stoneblower is taking some of the strain out of track maintenance. Richard Thompson reports.

Since railway privatisation three years ago, Britain's rail contractors have spent vast sums on state of the art equipment such as computerised tampers, massive track re-laying machines and a host of new utility road/rail machines.

Even Railtrack has got in on the act with a massive £12M investment in eight high-tech stoneblowers.

But heavyweight plant does not solve all maintenance problems. Most machines are designed to carry out large scale repetitive work on plain line track, and need to be complemented with smaller trackside plant to operate where irregular track shape rules out the high output machines.

There are impressive developments in the world of trackside plant. Together with contractor Amec, compressor manufacturer Factair - part of the Jackson group - has developed a handheld stone blower. This is a highly mobile compressed air system for correcting track level by pumping new, clean ballast at high pressure directly into the track bed.

The HHSB is designed for small scale stone blowing operations, such as at switches and crossings, where the large rail mounted stone blowers are unable to work.

Stone blowing is preferred to the traditional method of correcting track geometry with tamping because it gives a much longer life to the corrected track. Tamping, either with the large rail mounted machines or with handheld compaction tools, relies on rearranging and compacting the existing ballast. This can wear down the ballast and in time it can settle back.

The HHSB pumps ballast through a handheld funnel pushed under sagging track or sleepers. High pressure air from a mobile trackside compressor blasts the stones into position.

'It started with a phone call from Amec asking us to design the compressor for the hand tool they had developed,' explains Factair managing director Tim Curran.

'We ended up taking over the product, and redesigned the lance to get the velocity of stone flow in the nozzle right. One of the problems was to get the capacity from the compressor to blow different sized ballast. It can now blow all sizes up to about 22mm.'

The HHSB replaces the backbreaking method of measured shovel packing which required workers to sprinkle layers of new ballast under the affected track using cranked shovels.

'The HHSB is faster, less labour intensive and the finish lasts longer,' says Curran. 'It also compacts better than a shovel.'

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