South Devon Diesel Traction, SDDT

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"Class 33s" were built for British Railways Southern Region by the 'Birmingham Railway Carriage and Wagon Co. at Smethwick. The first few, including ours were built in 1959 and were first allocated to Hither Green in Feb 1960 They were fitted with 1550hp Sulzer engines and Crompton Parkinson elctrical gear, hence their nickname of "cromptons."

They were state of the art for their time, boasting both air and vacuum train brakes, electric train heat, driver's controls at all four corners, to make shunting easier and the best power to weight ratio of their time for a diesel electric loco.

They were intended for mixed traffic work from pick up freights and shunting to fast passenger work and did everything in between! They were unusual in that they were almost the only diesel locos the Southern Region had, and until the end of their lives, no other regions had them.

sulzer brochure
A Sulzer brochure showing a class 33.


The Wheel arrangement is 'B-B' (i. e. the locomotive has two bogies, each of which has two individually-driven axles). The locomotive may be operated singly, or may be coupled, to form a two-unit or a three-unit locomotive, with other locomotives which carry the 'blue star' coupling symbol.

Some locos were modified to work 'push pull' with '4TC' sets, these were rakes of four coaches that were to all intents and purposes Southern Electric Multiple Units with driving cabs but with out traction motors. They were either coupled to full 'EMUs' or to the modified class 33s. Locos like ours were called 'KAs' and in the 70s re numbered 33 0xx, the modified ones were known as 'KBs' and renumbered 33 1xx. Also a handfull were built to a narrower loading gauge to work the Hastings line, these were known as KCs and later renumbered 33 2xx.


Weight in running order with full fuel: 73.5 tons
Weight in running order with half fuel: 72 tons
Number of traction motors:4
Continuous tractive effort:26,000lbs
Max Tractive Effort: 45,000lbs
Gear ratio: 62/17
Driving wheel diameter: 3ft 7in

Length over buffers: 50ft 9in Height:12ft 8in, Width:8ft 10in.
Wheelbase of one bogie: 10ft 0in
Distance between bogie centres:29ft Oin
Minimum curve negotiable: 4 chains radius

Total fuel capacity: 800 gal
Total coolant capacity:227 gal
Lub oil Capacity: initial filling 108 gal
and 70 gal required for an oil change. Total Sand capacity: 2 cwts
Maximum permitted speed: 80 mile/h


MAIN GENERATOR Type, Crompton CG391-A1;
Output - continuous 1012kW
Rating - continuous 1760 amps

continuous output 57 k.w.

TRACTION MOTORS (4) Type Crompton C171-C2
Rating (continuous) 440 amps, Gear Ratio 62:17

ETH GENERATOR Type, Crompton CAG392-A1
ETH Index:48

Early 33
Early 60s Photo of class 33s
Source: unknown.

33 layout
Class 33 layout


Shows the layout of the loco's major componants.

sulzer brochure
Sulzer Brochure circa 1960


Type: Sulzer 8LDA28, One Napier turbo charger and interccoler.
Cylinder Formation: 8 cylinder inline.
Continuous Rating: 1,550bhp at 750rpm
Power at Rail: 1,215bhp Bore: 11.02 inches
Stroke: 14.16 inches
Lub oil Capacity: initial filling 108 gal
and 70 gal required for an oil change.

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