DETAILS OF MOTOR, CLUTCH AND GEARBOX WORKING TOGETHER

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The first major assembly work took place at Bletchley Park on Saturday 26 May 2001. Prior to this only the frame could be viewed by the visiting public. The frame was completed in September 2000.

In the view above and below can be seen the gearbox consisting of three layshafts. The output shaft is nearest to the camera. To the left of this is a bevel gear fitted to a short dummy vertical shaft. This was replaced later by a full height vertical shaft which reaches to the top of the machine. Three sets of bevel gears then transmit the drive to the three horizontal shafts. Also on the vertical shaft will be six worm gears. These drive six worm wheels on cam shafts. The cams work mechanisms that rotate the middle and slow drums by ratchet action. The other, mating, bevel gear is not fitted to the layshaft at this time.

Towards the front of the picture can be seen the lower cover temporarily fitted in place and above this the hand shaft. A cranked handle can be fitted here to rotate the machine by hand and to set the timing. The timing handle resembles the starting handle once used on older cars.

A pair of bevel gears are fitted at the other end of the shaft and transmit drive to the input lay shaft. The hand shaft rotates whenever the machine is running. A protective sleeve is fitted over the end of this shaft now that the covers are fitted.

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Above is the view of the gearbox and clutch taken from the clutch end. There are two solenoid coils at the bottom left of this picture which when powered, pull the armature upwards. The arm on which this is mounted is pivoted on a hanging link at the centre. Therefore its hooked end will drop down and clear the clutch "spider". The four pointed "spider" is made in two sections one of which, when released, will move against the other under spring pressure. This relative movement is amplified to allow the main dog to engage in the main driving pawl. Drive will then be transmitted throughout the machine. The motor can then be switched to full speed.

When a stop is detected the motor will slow down to half speed and the clutch solenoids de-energised. A spring will then raise the hooked end of the arm which will catch the next point of the four point "spider". The two sections of the "spider" will then be forced to rotate against each other resulting in the main dog being withdrawn from the main ratchet. The motor and input shaft will then idle at half speed until power is removed from the motor.

Volunteers who made this Milestone possible

 

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