Axial Drive Regeneration Resistor Replacement

Prerequisites

Table 4. Safety

electrocution hazard
voltages present in gantry
use proper lockout/tagout procedures from the safety section of the service documentation when stated during procedure. this procedure includes work directly in the gantry power pan.

Overview

This procedure describes the steps necessary to install a new axial regeneration resistor assembly into the axial drive assembly.

This procedure uses many screw, lock and flat washer combinations. Make sure the order of installation has the lock washer positioned between the flat washer and head of the screw.

Remove gantry right side cover and disable Axial drive and HVDC service switches from the service switch panel.

Refer to Replacement > Gantry > Enclosure > Gantry Side Covers Removal and Re-Install.
Position the tube at 4 o'clock position for easy access to brake assembly.
Disable the 120 VAC service switch. Remove all system power at the Main Disconnect panel and use proper Lockout/Tagout procedures.
Remove the gantry left side, top and front covers. Connect the cover E-stop circuit to the terminators on the gantry.
Loosen cable clamp and disconnect brake resistor cable from X3 port of axial drive controller. Refer to Figure 1. Loosen and/or remove the side safety cover if needed for extra space when removing cable.

note: Take note of the position of the resistor cable before disassembling. Different gantry models will have different routing for this cable.
Remove existing brake resistor assembly from axial drive assembly using a 5mm hex wrench. Refer to Figure 1.

Figure 1. Axial drive cable connection and mounting points

Mount the resistor assembly to side of axial drive box with two (2) M6 screws, lock washers and flat washers using a 5mm hex wrench. Refer to Figure 1 and torque according to the table below.

Table 6. Torque Table for M6 screws
8 N-m 70 in-lb 6 lb-ft 80.6 kg-cm
Route resistor cable the same way it was routed on the previous assembly and connect into the X3 port of the axial drive. Refer to Figure 1. Tighten cable clamp around cable. Loosen and/or remove the side safety cover if needed for extra space when installing cable.

Fasten the side safety cover on the tilting assembly if loosened or removed during previous steps.
Install the gantry front cover, top and left side covers.
Turn on the Axial drive, HVDC and 120VAC service switches from the service switch panel.
Install the gantry right side cover.