Brief History of Diesels on the Helston Branch




With the Helston Branch closing competely on 4th October 1964 diesel locomotives were never a main feature on the line. However, in the later years North British Class 22 diesel-hydraulic Bo-Bos were to be found working the route. It was in fact one of these such locomotives that hauled the final passenger train into Helston.

On the 3rd November 1962 at apx 20:45 class 22 no D6312 arrived at Helston with six coachs forming the last ever passenger train over the line. The train returned along the branch empty. D6312 was delivered new to British Rail in January 1960 to Plymouth Laira depot. It was from the same depot it was withdrawn in May 1971 to be cut up at Swindon in January 1972. All 58 members of the class were withdrawn around the same time and none have survived. Therefore the sight of a class 22 on the Helston branch will never be repeated! After the final passenger train class 22 locomotives continued on the branch working goods trains until the final closure of the route on 4th October 1964.


(24.07.62) Class 22s at Helston: D6317 stands to the left on a goods train with D6311 alongside on passenger.

Class 22s were the only class of mainline diesel to work the Helston branch. Due to their non-standard equipment, and BRs' decision to adopt diesel-electric transmission as standard , the fleet was phased out of service from 1968 with the final locomotive withdrawn in 1971. If the Helston line had survived longer the class 22s would probably of been replaced by the class 25s as was the case across the rest of the south west.

Just as a point of interest the last class 22s left Cornwall on the 3rd January 1972 when class 25 no 5180 towed class 22s nos 6336+6338 away from St.Blazey for storage at Bristol Marsh Junction after collecting 6333+6339 from Exeter also.


  • North British Class 22 Technical Details:

    1957 BR number range:

    D6300-D6357

    Former class codes:

    D6300-D6305 - D10/2A, later 10/4A
    D6306-D6357 - D11/5, later 11 /4A

    Built by:

    NBL

    Introduced:

    1959-1962

    Wheel arrangement:

    B-B

    Weight (operational):

    65-68 tonnes

    Height:

    12ft 1Oin

    Width:

    8ft 8in

    Length:

    46ft 8 1/2in

    Min curve negotiable:

    4 1/2 chains

    Maximum speed:

    75mph

    Wheelbase:

    34ft 6in

    Bogie wheelbase:

    8ft 6in

    Bogie pivot centres:

    23ft

    Wheel diameter :

    3ft 7in

    Brake type:

    Vacuum

    Sanding equipment:

    Pneumatic

    Route availability:

    4

    Heating type:

    D6300-D6305 - Steam-Spanner Mkl D6306-D6357 - Steam - Clayton or Stones

    Multiple coupling restriction:

    D6300-D6305 - Orange Square
    D6306-D6357 - White Diamond

    Brake force:

    29 tonnes

    Engine type:

    D6300-D6305 - MAN L12V18 21A
    D6306-D6357 - MAN L12V18 21B

    Engine horsepower:

    D6300-D6305 - 1,000hp
    D6306-D6357 - 1,100hp

    Power at rail:

    ?? hp

    Tractive effort:

    D6300-D6305 - 40,0001b
    D6306-D6357 - 38,0001b

    Cylinder bore:

    7 3/4in

    Cylinder stroke:

    8 1/4i n

    Transmission type:

    Voith LT306r

    Fuel tank capacity:

    45Ogal

    Cooling water capacity:

    135gal

    Lub oil capacity:

    38gal

    Boiler water capacity:

    50Ogal

    Boiler fuel supply:

    From main tank