Carriage locking mechanism

* Translation by Eric Schurmann

I) Carriage locking mechanism (1852)

This extract from the 1865 Patent, summarises perfectly the advantages and disadvantages of the hook that was used on the 1852 machines:

"In the old machines (T1850), the carryover worked by means of a double inclined steel plane, fixed to the dial, which pressed against the carryover lever and disengaged it so that it descended vertically. But it so happened that, if several inclined planes were pressing on the carryover levers of several dials at the same time, the levers, instead of descending, made the mobile carriage lift up. This weakened the meshing between the bevel wheels and the dials so that the dials showed false results.
To overcome this problem, a steel hook (T1852) was introduced which engaged with the stepped tooth cylinder in such a way that , as soon as the crank started to turn, it came down on the carriage plate and prevented it lifting. This hook released the plate as soon as the crank returned to its starting point and allowed the plate to lift and to slide. But there was one big disadvantage to this hook system in that if the crank was jammed in the middle of a turn, the hook would not release the plate so one could not lift it and it was extremely difficult, if not impossible, to cure the cause of the jam."

Thomas very quickly put in place a new, and more reliable, carryover system but that's another story….



Detail of the mechanism