Andrew Briddon Locos

Andrew Briddon Locos

preserved railway vehicles

F C Hibberd "Planet" 4wDM: Pluto

pluto rowsley

Works Number 3777
Weight 22tons (in working order)
Wheel Arrangement 4wDM
Power Unit Foden FD6 (2-stroke)
Rating 105bhp at 1800rpm
Present Location Darley Dale
Photos Gallery

Post war, F C Hibberd, under the 'Planet' trademark, built a range of diesel-mechanical shunters at Park Royal in London usually based around a Dorman engine and the Wilson 4-speed box, the latter incorporated into their own casing with a forward/reverse section. It is said that a new design was chalked out on the workshop floor, the prototype built to those outlines, and then the draughtsmen came in to measure it and draw it for later copies! Standard models included an 18ton using the Dorman 4DL (77.5hp) and 20 and 23 ton models using the Dorman 6DLIII 123hp, (later Dorman 6KUD). In their last few years they were represented in the north of England by Thomas Hills, resulting in a 24ton 4w DH, using either the Dorman 6KUD or the Leyland 680, driving the Planet forward/reverse box through a Twin Disc CF10000 series torque converter. After Hills and Hibberds separated in 1959, the company went into decline, being taken over by Butterleys and relocated to Ripley, Derbyshire; manufacture ceased c.1964.

pluto cvrDuring the 1950s the Navy re-equipped its dockyard/depot loco fleet, and specified the Foden FD6 (105bhp) engine as prime mover. The Foden was a 2-stroke engine with an aluminium alloy crankcase, and having low magnetic signature was employed for Navy minesweepers, so was a 'standard' engine for use in similar power ranges. Hibberd's thus developed a version of their Planet with this engine, incorporating an additional distinctive ballast block at the front to arrive at a weight of 22tons. As the Foden ran at 1800rpm, and the Dormans and the Wilson change-speed epicyclic components used in the Hibberd gearbox ran at 1200rpm, a 1.5:1 step-down box was added between the FD6 and the usual Planet transmission. Quite a few were built, mostly standard gauge (Devonport, Portsmouth, Chatham, Rosyth etc) but n.g. versions were produced, two of which ended up on the Festiniog and Welsh Highland Railways (though much modified). An extension to the casings on the right hand side of many locos contained an Enfield engine and rotary exhauster to provide the "suck" for vacuum brake installations. The fuel tank however, was located in the back corner of the cab, and spillage during filling could make the cab floor treacherous.

Pluto' was one of 3 built in 1955/6 for the Navy at Rosyth, remaining in service until it was put up for sale in 1992. Bought by YEC, the crankshaft of the Enfield engine was found to have snapped so it was decided to remove the vac brake gear (for which no forseeable requirement was foreseen) and relocate the batteries and fuel tank into the casing section thus vacated. In this form it was put out as a hire loco in various places but during its last job at Onllwyn coal depot in South Wales it began to develop engine problems and corrosion had partially seized its brake rigging. When it returned to YEC's base at Long Marston in 2000 it was intended to carry out an overhaul, but this had got little beyond opening up the engine when YEC ceased trading in 2001.

'Pluto' had always been a favourite of Andrew's father so Andrew took the opportunity to save it from scrap. Then one Saturday morning, a friend exploring a large scrapyard in Hampshire found a complete Foden FD6 - presumably more redundant Navy equipment since it was set up on a skid as a self-contained power unit - and after a flurry of phone calls, a deal was struck and the engine came to Long Marston. It seemed as though this was a fully reconditioned engine, since inhibiting oils were found in various places, and other than superficial damage to the external oil filter assembly was in first class condition. 'Pluto's' old engine and fluid coupling were removed and the new unit dropped in place. The damaged filter assembly was however replaced with a Fleetguard header to suit a common spin-on filter. Such is the joy of such modifications that it was not initially realised that the oil pressure relief valve was located after the filter assembly, and on a cold start-up, the oil pressure was sufficient to 'dismantle' the spin-on filter with spectacular results! Once diagnosed, an additional relief valve was incorporated to prevent the problem recurring!

Volunteers at the Chatham Historic Dockyard welcomed 'Pluto' on its arrival in March 2006 and it saw considerable use over the next couple of years, including an excellent repaint from the mixed green/red/grey it had been wearing to dark green. The loan period was terminated by Chatham management in 2009 and on the 11th December the loco left Chatham for a new home at the Colne Valley Railway, Castle Hedingham, Essex.

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It left Castle Hedingham again on the 11th February 2011, and transferred to Peak Rail where Andrew proceeded on re-instating the vacuum brake installation. The loco relocated to the DVLR at Murton, York on the 29th July 2011 but after 4 years at the DVLR, retuirned to Derbyshire in August 2015 for attention.

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