Restoration of the 1132 printer carriage mechanism - part 1

LOOSENING UP THE SHAFTS AND BEARINGS OF THE GEARBOXES

The carriage motor runs continuously as does the main printer motor. A worm gear on the end of the motor turns parts of the gearbox, so they are always turning as long as the motor switch is on. 

Continually turning parts marked in green

The left and right side gears marked in green across the center of the picture above turn at different speeds. A clutch mechanism attached to each gear can couple its motion to the center gears. When either clutch is activated, the platen begins turning at the speed dictated by the left or right gear. The right gear turns the platen at about 150 RPM while the left gear makes the platen turn at 70 RPM. 

Gears marked in yellow turn in slow speed mode

Gears marked in red turn for high speed mode

When either the yellow or red gears are turning, they also turn the platen through a driving gear and a second detent gear ensures good vertical line alignment. 

A detent gear in the gear box has notches in it at each print line position into which a spring loaded detent lever will fall. This ensures that the platen stops precisely at the next line position even if the solenoid deactivation is somewhat imprecise. 

I worried about clearing up the clutches as they are somewhat complex with plenty of spaces for lubricants to freeze up the works. 

exploded view of a clutch

I have been seeping clock oil everywhere I can reach but not getting a significant improvement in turning resistance. This is going to take some time and might require substantial disassembly. 

MOTOR TEST

The 48VDC motor wouldn't turn with the very sticky gear train connected, but once I pulled the worm gear off of the motor, it spun up nicely with my bench power supply. It is a 50W motor but when free spinning it was consuming around 32W. I tried to get some clock oil seeping into the front bearing of the motor, hoping it spins even easier in the future. 

Worm gear removed

shaft ready to spin when 48V applied

CB RESTORATION

The CB (cam driven switch) consists of a cam gear that is on the same shaft as the carriage control tape drum. It has slots for each line position of the platen.

CB microswitch

The microswitch has a spring loaded plunger on the top which rides on the cam gear. The purpose is to send a signal back to the 1130 printer controller logic every time the plunger enters a slot. The printer controller logic activates the solenoid to activate a clutch. That causes the platen to start rotating at about 70 RPM. When the plunger falls into the next slot on the cam gear, the printer controller releases the solenoid so that the platen comes to a stop.

The plunger needed to be freed up to move in and out of the slots. Once it did, I concentrated on the conductivity of the contacts. After thirty minutes of work, the resistance of the points was still above 220 ohms. The corrosion from the rodent urine soaked really deeply into the contact metal.