Linear Bearing Guideway; Carriage Home Position Sensor; Inner Shrouds - AGFA Avantra 36/44 Service Manual

Section I: Imagesetter
Both encoders are high count precision rotary encoders. One of the encoders (ana-
log) couples directly to the friction wheel shaft and is used to feed back carriage
velocity errors. The other encoder (digital) mounts inside the carriage housing and
is preloaded to make direct contact with the guide rail. This encoder feeds back
carriage position errors. The carriage electronics, which make small adjustments in
torque to the servo motor to ensure proper carriage position and velocity at all
times, process both velocity and position error signals.

2.13.2 Linear Bearing Guideway

The linear bearing guideway system consists of two (2) recirculating ball bearing
units. These units each mount to one side of the carriage housing. The housing
rides in a fixed V-groove rail mounted to the upper structure. The friction wheel
extends from the opposite side of the carriage housing, which rides on a flat rail
mounted to a parallel surface on the upper structure.

2.13.3 Carriage Home Position Sensor

A carriage home position sensor (optical) establishes a calibration position for the
carriage. The calibration position establishes a reference point to start imaging.

2.13.4 Inner Shrouds

The inner shrouds, used for guiding media during feed sequences, mount directly
to the carriage assembly and travel with the assembly through the drum. Refer to
Figure 2-10. The shrouds also reduce noise and prevent media fogging.
Two inner shrouds attach to the center of the carriage mount. Each shroud has
three sets of brushes and one outrigger. Four screws attach the shrouds to the
mount. Both shrouds can only be removed from the left side of the imagesetter;
i.e., to remove the right inner shroud, you must first remove the one on the left.
Functional Analysis 2-21