The moving carriage occupies most of the front half of the machine.
It contains the accumulator register and its tens-carry mechanism, the counter register, the register clearing mechanisms, and part of the automatic shifting mechanism.
This page gives an overview of its construction and mounting. The various carriage mechanisms are described in detail in the sections following.
The carriage body measures about 400mm long, 140mm deep, and 100mm high. The completed assembly weighs just over 6kg, and contains over 900 manufactured parts.
The mechanism consists of several long sub-assemblies, which are mounted on and between a pair of substantial brass end plates.
The carriage is supported on four steel rollers, which travel on steel rails attached to the bedplate.
This view shows the right-hand carriage end plate in its installed position. The rest of the carriage mechanism has been removed to show the rollers and their supporting rails. The left-hand end is similar.
The rear rail is a length of 20 x 5mm steel plate which is attached to the bedplate with two brass angle brackets. The flanged roller at the bottom rear of the end plate travels in a slot cut into the rail. The slot limits the travel at each end, and holds the carriage in place if the machine should be inverted in transit. The flange prevents the carriage moving rearward.
The front rail is a flat strip of steel which is set into a slot milled into the cast-iron bedplate. A brass strip at the edge of the rail stops the carriage sliding forward. The bottom front roller is 18mm diameter and 8mm wide, and is attached to the end plate with a substantial shouldered screw.
A cross-bar of 15 x 5mm steel runs between the two pillars at the front corners of the machine. The top roller on the end plate runs under the cross-bar to help support the front of the machine's top panel. (The panel is not heavy, but the operator may be tempted to lean on it). The top roller also serves to hold the front of the carriage down during service or transit.
Note the indentations made by the bottom roller at the index positions along the front rail. There are similar but smaller indentations in the rear support rails. The depth decreases towards the less-used positions to the left.
The carriage installed.
This view shows the mounting points with the carriage fully assembled and installed.
This view is taken looking along the camshaft from the right-hand end, with the carriage in its left-most position.
The legs of the carriage end-plates straddle the camshaft and the front cross-shaft support pillars. The clearances behind and below the carriage are only about 1mm. The edge of the front cross-shaft bearing plate (on the front face of the pillar) has to be chamfered to allow the carry drum to pass.
The end of the differential shifter plate is visible between the horizontal arms of the pillar. The register gears are directly above.