Selectric Resources

 

INTERPOSER RELEASE

An operation is activated by depressing one of the operational keylevers (Figure 2).

 

When an operational keylever is depressed, a lug on the keylever pawl contacts the interposer, forcing it down to release the interposer latch from the interposer latch plate (Figure 2).

 

INTERPOSER FUNCTIONS

As soon as the interposer latch has cleared the latch plate (Figure 2), the interposer is pulled to the rear by the interposer spring. When the interposer moves to the rear, it performs two functions:

 

1. A lug on the bottom of the interposer contacts the clutch release arm, rotating it down at the front, allowing the cam wheel to be released. When the clutch release arm.releases the cam wheel, the cam wheel will rotate, allowing the cam pawl to engage the operational clutch ratchet. The operational clutch ratchet is attached to the operational shaft and rotates when the machine is on. The operational cams are mounted on shoulders of the operational clutch ratchet. The operational cams remain at rest on these shoulders until the cam pawl engages the ratchet. When the cam pawl engages the operational clutch ratchet, the cam turns with the operational shaft and ratchet.

 

2. An extension at the rear of the operational interposer positions an operational latch under its cam follower.

Figure 2 — Operational Control Mechanism(At Rest) (Right Side View)

 

CAM FUNCTIONS

The rotation of the operational cam assembly performs two functions (Figure 3).

 

1. The cam follower follows the cam surface of the operational cam from the low point to the high point. This causes the cam follower to pivot around its mounting shaft, pulling down on the operational latch. The power to operate each of the operational functions is taken from an operational latch. A detailed description of each operational function, starting at the operational latch, can be found in their section of this manual.

 

2. The operational cam follower also contacts the interposer restoring lever and causes it to restore the operational interposer forward, allowing the interposer latch to relatch on the interposer latch plate.

 

CHECK RING

As the operational cam completes its rotation, the cam wheel contacts the clutch release arm, which pivots the cam pawl out of the operational ratchet (Figure 4). Continued rotation of the cam allows the check pawl to engage a notch in the check ring which is mounted on the opposite side of the cam (Figure 5). The check pawl holds the cam in the rest position, ensuring that the cam pawl does not reengage the operational ratchet until the next operation.

Figure 4 — Cam Wheel (Right Side View)

Figure 5 — Check Ring (Left Side View)

 

REPEAT OPERATION

Repeat operation of an operational mechanism can be done by preventing the interposer from relatching against the interposer latch plate (Figure 6). A second lug, called the repeat lug, on the keylever pawl is used to prevent the relatching of the interposer when a keylever is depressed in the repeat mode. In the case of carrier return, the repeat lug on the keylever pawl is formed to the right above the index interposer. Depressing the carrier return keylever into the repeat mode causes the index interposer to be released, resulting in additional linespacing.

Figure 6 — Keylever Pawl Operation (Right Side View)