THE SIGNAL BOX

OVERSEAS

MECHANICAL FRAMES
Swedish State Railway (SJ)

by John Hinson

Crank-handle interlocking frame
Photograph from the collection of Dr J W F Scrimgeour

The first interlocking frames appeared in Sweden in 1888, and were made by Max Jūdel in Braunschweig. They were of the crank-handle type, working points and signals by the double-wire system. Later, the Jūdel frames were manufactured under license in Sweden, and similar frames were also produced by other firms.

The cranks themselves pull forward so as to not foul the adjacent handles. Note the indicators above the cranks, showing the position of the points or signals.

The interlocking is contained in the box above the handles. A release key can be seen in a lock on top of this casing, above the third handle from the right.

The crank-handle frame became popular in Sweden as it saved both the cost of erecting a formal signal box and the staffing. The frames would be mounted on the platform in front of the station building and would be operated by the station master.

Crank-handle interlocking frame at Stromtorp
Photograph from the collection of Dr J W F Scrimgeour

A different style of crank-handle frame, operating in much the same way as that in the previous photograph. This example was located at Strömtorp.

Double-wire and power frames at Stocksund
Photograph 1927, from the collection of Dr. J W F Scrimgeour

Centrepiece of this interesting display of equipment is a more conventional type of double-wire frame. At the far left is a small power-operated frame whilst on the right is the block signalling apparatus.

The photograph was taken at Stocksund in 1927.

About the photographs

Additional notes by Per Olofsson



Comments about this article should be addressed to John Hinson