Style 'K' mechanically locked lever frame

The Westinghouse Brake & Saxby Signal Co. Ltd produced the Style 'K' mechanically locked lever frame from 1912, and a total of 35 units were shipped numbered 1 through 35, the 'L' series followed starting at L36.

It was W.A. Pearce at Westinghouse who designed the Style 'K' power interlocking miniature lever frame with its mechanical locking between the levers, and with the locking complexities of the Cannon Street lever frame with its conditional locking of signal against signal through every conceivable alternative route, that eventually led Westinghouse to develop the Style 'L' lever frame.

As far as the differences between B and K go there aren't really any other than the K usually had a greater number of contact bands because these were normally used for all-electric installations whereas the B was first designed for electro-pneumatic operation. Both had teak casing but LT companies often went for steel, similar to the L and N styles. I guess there were probably subtle changes to materials and parts between the B and K as there was a time separation between the first Bs and the introduction of the K so opportunity would have been taken to make improvements or economies. So the answer is that I've not come across any significant difference, it's more a case of marketing a "new" version by Westinghouse at the time because it's also not unknown for Ks to be used on electro-pneumatic jobs.

It was the sheer time and cost and complexity in doing a major relocking exercise that the Southern Railway ordered for Cannon Street. It actually took a month to physically fit each individual new piece of locking to the lever frame and test it before re-installing the original locking to allow trains to run normally until all the new interlocking was ready for installation.

Also another major consideration in the development of the Style 'L' lever frame was the sheer weight of the London Bridge 'K' style lever frame weighing in at 23 tons for its 311 levers. This kind of weight at 23 tons needed a very strong mechanical support for the lever frame itself to ensure that the frame did not twist or become mis-aligned at any time so that the mechanical lever locking could never be compromised and cause what is know quoloqly as a wrong side failure.

The first table in Green, shows all the locations of all frames supplied and installed by Westinghouse Brake and Signal Co. The second table in Yellow, lists all known preserved style 'K' lever frames in the UK.

Westinghouse Supplied & Installed Style 'K' Power Lever Frames used in the UK
Signal Box Name	Railway	Frame no.	Capacity	Point Levers	Signal Levers	Special Levers	Spare Levers	Frame open	closed
Borough Market Junction	Southern Railway		35	11	23	0	1	17th June 1928	April 15th 1976
London Bridge	Southern Railway		311	216	79	?	?	Sunday 1st December 1929	April 15th 1976
Cannon Street	Southern Railway		167	78	38	6	45	27th July 1926	Fire 5th April 1957
Charing Cross	Southern Railway		107	24	69	1	6	27th June 1926	15th April 1976
Manchester Victoria West Junction	L.M.S Railway		95	?	?	?	8	10th March 1929	8th August 1993
Manchester Victoria Deal Street	L.M.S Railway		103	?	?	?	?	10th March 1929	31st July 1998
Manchester Victoria Irwell Bridge Ground Frame	L.M.S Railway		15	?	?	?	?	10th March 1929	13th March 1988
Southport Chapel Street	L.M.S Railway		81	?	?	?	12+6	1917	20th March 1994
St Lukes			103	?	?	?	?	1918	30th Nov 1969
Baker Street	London Transport		39	12	20	5	2	6th A\|pril 1924	11th June 1988.
Edgeware Road	London Transport		39	14	18	4	3	10th October 1926	still open
Moorgate	London Transport		11	2	9	0	0	15th Feb 1941	6th December 1965.
Malmö	Sweden		75	33	41	3	?	1925	1982

Surviving / Preserved Westinghouse Style 'K' Power Lever Frames
Signal Box Name	Railway	Parts From	Capacity	Point Levers	Signal Levers	Special Levers	Spare Levers	Date in use &/or further information
Wood Bay	Holiday Island Miniature Railway Co	Deal Street Manchester Victoria	16
Amwell Junction	East Herts Miniature Railway	Hyde Park Corner	24	7	11	3		currently in use

Style 'K' Frames exported abroad by WB&S
Signal Box Name	Railway	Order Date	Capacity	Point Levers	Signal Levers	Special Levers	Spare Levers	Date in use	Date out of use
Bombay 'A'	India	?	?			-		1930	???