and against which pin 88 abuts the step 93a at one range end of cam track 92 fig7 is so dimensioned that contact finger 76 is retained in a position laterally outside cam track block 70 the switch cam 96a associated with this step 93a has abutment surfaces 99a 99b 99c against which contact member 77 engages and by which the position of the contact finger is determined handwheel 83 is marked with letters fig1 a to h corresponding to the various arrest positions and can be set against a corresponding mark 100 provided on post 2 the design of control assembly 53 for controlling the feed motion of feed dog 27 is substantially identical with that of control assembly 54 the sole differences are the shape of cam track portions 69 and a single abutment surface 99c of switch cam 96a for pivoting contact lever 75 into a position in which the maximum feed is adjusted worm 71 of control assembly 53 is engaged with shaft 13 handwheel 83 of control assembly 53 is marked with letters m n and o fig1 which can be set against a corresponding mark 101 on post 2 in the position o contact lever 75 is in a position laterally of cam back block 70 i e the function of.