THE SIGNAL BOX

LEVER FRAMES

BRITISH RAILWAY LEVER FRAMES

McKenzie & Holland lever frames

McKenzie & Holland No.2 Pattern lever frameMcKenzie & Holland No.2 Pattern lever frame

Whilst patent drawings exist of early types of lever frame, it is sometimes difficult to identify examples owing to the lack of general drawings of the shape of the lever frame.

This example bears many of the hallmarks of McKenzie & Holland's factory, such as the multiple notches on the quadrants, but bears little overall resemblance to later products. The levers appear to be pivoted above floor level and the locking is contained in the casing behind. This suggests that this is in fact a No.2 pattern dating from the late 1860s. The No.1 and 2 models pioneered McK&H's cam mechanism to reduce the travel of the locking, but were quite different to the eye as the number one had the lever pivot and locking below floor level. This example totals ten levers in size, although lever 7 has been removed. Typical McKenzie & Holland brass plates attached to the levers identify the lever numbers to the signalman.

As on many frames of the era the central group of levers controlling pointwork stand forward of the position of the signal levers.

This example is preserved at the York Railway Museum.

McKenzie & Holland early pattern lever frame

Nearly all McKenzie & Holland lever frames had a type number, although in many cases the difference were slight. Not all numbers appear to have gone into production.

This example does not appear to fit the bill for any of the recognised frame types. Distinct features are the widely spaced levers and the diamond tread pattern on the quadrant plates. This latter is generally associated only with McKenzie's No.1 pattern, although that type featured flat floor plates and only one raised catch guide.

This example is at Mow Cop, more details of which can be found in the Photo Gallery.

McKenzie & Holland No.5 Pattern lever frameMcKenzie & Holland No.5 Pattern lever frame

In 1873, McKenzie & Holland introduced a new design of lever frame that was to set the style of all frames to come. Although the below-floor pivot point of the levers was in the conventional central position, a dogleg on the shape of the levers allowed them to stand vertically when in the normal position. This had benefits in allowing the signalman to reach the lever more easily, and get a better pulling angle.

The locking mechanism was a development from the above type, known as Cam and Soldier locking.

The No.5 frame was probably the most common type, with levers spaced at 5" centres, but similar frames with variations were No.4, 5A, 6, 6A and 8. This type of frame can easily be identified by the multiple notches on the quadrants for the signal levers, allowing a crude form of signal wire adjustment.

This example is at Leek Brook Junction, more details of which can be found in the Photo Gallery.

McKenzie & Holland No.12 Pattern lever frameMcKenzie & Holland No.11 Pattern lever frame

The next development took place in 1886, when a new type of interlocking known as Cam & T-bar locking was introduced. At operating floor level, the levers look very similar to the 1873 designs, except that the number of notches for the signal levers were reduced to two.

The example shown here has 5" spaced levers, but a few existed with 4" centres (No.12) and a few existed at 4½" (no.9).

Quantities of this type was used by the Great Eastern, Great Northern, North Staffordshire, Brecon & Merthyr, Taff Vale and Highland Railways and in smaller numbers elsewhere.

This example is at Dingwall South; more details can be found in the Photo Gallery. Other examples can be seen at Achnasheen and Forres East.

McKenzie & Holland No.13 Pattern lever frameMcKenzie & Holland No.13 Pattern lever frame

In the early 1890s, McK&H adopted tappet locking, driven through a cam just below floor level. Again, the type visually follows earlier styles, and this type is difficult to distinguish from the 1886 design without visiting the locking room. The second notch on the quadrant does not appear to have been used on this type.

Most frames of this type were built to 4" centres; the 5" variant was the No.14.

This type was found extensively around the Great Eastern, Great Northern, North Staffordshire, Rhymney and Highland Railways and in smaller numbers elsewhere.

This example is at Rhondda Fach Junction South, more details of which can be found in the Photo Gallery. Another example is illustrated at Maud Foster.

McKenzie & Holland No.16 Pattern lever frameMcKenzie & Holland No.16 Pattern lever frame

A variation of the standard tappet types was introduced in 1903 for the benefit of the North Eastern Railway.

The significant visual difference is the presence of just one reverse notch on the quadrant, allowing the full stroke of the lever to be used.

A later variation with 4" centres was known as the No.17.

This type was standardised upon by the NER, and the practice was continued by the LNER (Northern Division) and BR (NE).

This example is at Wolsingham, more details of which can be found in the Photo Gallery. An example if the no.17 pattern can be seen at Low Gates.

McKenzie & Holland Leyton Rebuild lever frameMcKenzie & Holland "Leyton Rebuild" lever frame

The Great Eastern carefully economised by saving redundant lever frames. The signal workshops at Leyton would re-assemble parts into frames for re-use.

Obviously, a number of varieties existed, but one common feature of many of these frames is the absence of the multiple notches in the quadrants that one would expect to see on frames originating from the 1873 designs.

Frames of this type existed in 5" and 4" versions - this is one of the latter.

The example shown is at Attleborough.

Index to this section