IBM 6400 series Maintenance Manual page 39

Hammer Bank Assembly
The hammer springs are grouped in comb-like assemblies mounted on a
solid hammer bank. Both the number of hammer springs per hammer spring
assembly and the number of hammer spring assemblies on the hammer
bank vary according to printer model:
6400–004/–04P/–005/–05P/–050/–P50: seven 4-hammer assemblies, for
a total of 28 hammer springs
6400–008/–08P/009/–09P: seven 7-hammer assemblies, for a total of 49
hammer springs
6400–010, –10P: six 10-hammer assemblies, for a total of 60 hammer
springs
6400–012/–014: seven 13-hammer assemblies, for a total of 91 hammer
springs
6400–015: six 17-hammer assemblies, for a total of 102 hammer springs
Shuttle Drive Motor
The shuttle drive motor is built into the shuttle assembly casting and drives
two connecting rods on a crankshaft. (See Figure 11.) The small end of one
connecting rod attaches to the hammer bank; the small end of the other
connecting rod attaches to a counterweight frame surrounding the hammer
bank. (The hammer bank and the counterweight constitute the shuttle
assembly.) The rotary motion of the shuttle drive motor converts to linear and
opposing motion of the hammer bank assembly and the counterweight, in an
arrangement similar to that of a horizontally-opposed gasoline engine.
Mechanically, this design achieves the same benefits as this type of engine:
perfect primary balance, low vibration, and durability.
Each hammer spring is a stiff leaf spring with a cylindrical tungsten carbide
tip on the free end. (See Figure 12.) A permanent magnet is imbedded along
the length of the hammer bank and acts on the hammer springs through
individual pole pieces. The pole pieces magnetically attract and hold the free
end of the hammer spring under tension. This is called the retracted state.
Principles of Operation
39