The Western Regions Diminutive Class 22's

                                                                                                  (Photo courtesy, and copyright, Pip Davey)

Initially ordered as part of the BTC's pilot scheme locomotives, the first six (D6300 - D6305) North British built Class 22's featured the same configuration and engine as its sister Class 21 diesel-electric machines intended for introduction on the Eastern Region.The single NBL/MANL12V18/21BS engine was identical to the two fitted in the larger North British D600's and both classes of locomotive shared similar cab layouts and components. Unusually, both bodies and cabs were constructed from alluminium.

As with many of these pilot scheme locomotives, in November 1957, an order for 52 more machines was placed, more than a year before D6300 had been built. Cost per machine, £61,700. The final locomotive of the class, D6357, was delivered to the Western Region on 23rd October 1962. The units were designed with flexibility in mind, to be used singly for secondary work, or coupled in multiple for heavier duties. To achieve this, the gangway connectors in the nose ends, became of importance (at the time) and the front end styling reflected in this, enabling two locomotives of the same or different class, to be operated from the leading cab, and having the versatility for crews to pass between each machine.

The additional 52 locomotives saw the NBL/MAN engine uprated to 1100hp, and a different form of Voith transmission, the Voith-North British LT306r, a more compact and lighter unit. The 1100hp engines were to match the order being placed at the time for the NBL built D800 'Warships', again with a view, perhaps, to versatility in both multiple working and future engine changes between the classes. This relegated the pilot scheme examples to be only multiple unit compatible to the D600's. Further modifications on these higher powered machines saw an improved cooling system incorporated, and these locomotives were recognisable by a larger air intake grill on the bodysides.

The whole of the class differed again from all of the 'new' locomotives being delivered, by having spoked wheels and headcode discs hinged vertically instead of horizontally. Later in their lives the class were fitted with four character headcodes, sited in two boxes, either sides of the central gangway doors. NBL provided the modification for D6334 - 57 whilst Swindon dealt with the remainder. Unusually the six pilot scheme examples saw these modifications placed higher up on the fronts of the locomotives. Several of the NBL Type 2's lasted long enough to carry rail blue livery (all over blue, including the roofs, full yellow front ends, black buffer stocks and bogies), although early repaints emerged with non-standard small BR symbols and numbers in the 'slim' style typeface.
The D6300's were initially set to work in Cornwall and Devon handling all freight traffic and secondary passenger services not worked by DMU sets, including banking work for goods and passenger trains on the steep grades between Newton Abbot and Penzance, and could often be seen used as designed, as two locomotives coupled to form a Type 4 machine, but their downfall was their top speed of 75mph, and they were soon relegated to secondary passenger duties and local freight work. With the closure of many of the branch lines in the West Country the machines became spread across the whole of the WR. The introduction of the Brush Type 4's to the region saw the Class 52 'Westerns' displaced from the Paddington - Birmingham New Street services and transferred to West Country diagrams, further resulting in releasing the Hymek locomotives for Devon and Cornwall work. 18 Class 22's, the first of which being D6326, were thus released from the latter area and moved to Old Oak Common for London area work, and Reading diesel depot was extended to provide extra accommodation for diesel locomotive servicing. During the latter half of 1963 the platform ends at Paddington station were to be fitted with electric cables for connection to the steam heating boilers to enable them to operate without the locomotives engine running. A modification to each machine to enable this practice was required and it is doubtful that the plan ever reached fruition. The twilight of their careers found them regularly operating empty carriage stock between Paddington and Old Oak Common.
Withdrawals began in December 1967 with D6301, the remaining five pilot scheme examples followed in May of the following year. These six were always candidates for early withdrawal as their design differences lasted until their demise. The remaining 52 of the more powerful machines steadily succumbed to the scrapman over the next three years, with D6338/9 being the last in traffic, finally withdrawn on 1st January 1972. One machine, 6319, was the subject of an early diesel preservation attempt by the Diesel Traction Group which sadly came to nothing. (further details here). None of these historic Class 22's survive today.

Class History

Technical Specifications:

Class: BR Type B (2), later Class 22
Purpose: Mixed-traffic locomotives
Introduced: 1959
Original numbers: D6300 - D6357
Total built: Six pilot scheme, 52 production (Nos D6300 - D6305 by North British in 1959-60; Nos D6306 - 57 by North British 1959-62)
Engine: One NBL/MAN L12V18/21BS. No of cylinders and cycle - 12, 4-stroke. Maximum continuous rated output - 1000hp at 1445rpm (D6300 - D6305), 1100hp at 1530rpm (D6306 - 57)
Transmission: Voith-North British L306r (D6300 - D6305), Voith-North British LT306r (D6306 - D6357)
Performance: Maximum tractive effort - 41920lb at 27.6% (D6300 -D6305), 40180/40000lb at 27.6% adhesion (D6306 - D6357) Continuous tractive effort - 23900lb at 10.4mph (D6300 - D6305), 30000lb at 8mph (D6306 - D6357)
Braking: Air for loco and vacuum for train giving a brake force of 78.18% (D6300 - D6305), 73.84%-74.18% (D6306 - D6357) of loco weight in working order
Speed: 75mph (maximum permitted working)
Curve: 4.5 chains (minimum radius curve without gauge widening at dead slow speed)
Train heating equipment: Spanner Swirlyflo (D6300 - D6305), Clayton RO-100 (D6306 - D6325), Stone-Vapor OK4610 (D6326 - D6357), giving a steaming capacity of 1000lb/hr
Tank capacities: Engine fuel and train heating fuel - 450gal, Train heating boiler - 500gal