Works Number 4/71.
Brock is a coal fired, twin cylindered, narrow gauge steam locomotive to a freelance design.
Gauge: 9.5in (241.3mm)
Pressure: 110psi (max 120psi)
Cylinders: TBC bore x TBC stroke
Valve Gear: Hackworth
Length: 9ft (inc. tender)
Current Livery: Blue (no lining)
Brock was built over a three-year period commencing 1971 and completing in 1974 to a minimal budget and a basic design. It's crude construction still very noticeable today. The chimney used a discarded drain down pipe, several key design features such as counterweights on the return cranks were omitted, and a traction engine whistle was fitted. The cylinders were controlled by the Marshalls valve gear. Two side tanks fed an axle pump and a steam injector. The tender provided seating for a driver, secondary storage for water, and storage for coal. The locomotive was finished in a black livery lined in red. The locomotive was named after the school's badger mascot Brock.
Brock's initial running on the Downs Light Railway was hampered by technical problems. The boiler's dome location directly over the top of the firebox gave little space for the steam to collect. Consequently, the locomotive often primed and under performed. After modifications in the late 1970s, the locomotive became a reliable form of motive power on the Downs Light Railway. A significant rebuild was considered in the late 1980s, but was not pursued with the arrival of a new locomotive James Boyd (nee Tubby 2).
- 1977-1980 the locomotive was modified by Milner Engineering with an extended dome to the boiler to increase the steam space, revised arrangement of the water gauge, and removal of the axle water pump and fit of a secondary injector.
- 1993-1994 the boiler was retubed and studs replaced.
- 1995 the locomotive transferred from private ownership to the Trust.
- 1997 the locomotive was repaired by Allan Keef Limited, following a catastrophic failure of the valve gear. The Marshalls valve gear was replaced with the Hackworth valve gear. The axles were modified with new bearings and counter weighted return cranks.
- 2004-2005 the locomotive was overhauled by ArthogSteam. This included a new smoke box, new chimney cap, new exterior pipework, new bushes, and a livery change to blue.
- 2009 the boiler was eventually condemned and the locomotive was retired from service.
- 2017 a new boiler was commissioned with Denver Light Railway Limited.