FLYWHEEL GP 9Q7591 - Caterpillar

Introduction
Certain Telescopic Material Handling (TMH) vehicles have the 838797 Load Indicator Group installed. The load indicator group consists of a strain sensor, a display unit and associated wiring, and mounting hardware. When the load indicator group is installed at the factory, the strain sensor is bonded to the machine frame and a special procedure is used to set up and calibrate the display unit.The 838843 Display Unit and the 844241 Strain Sensor Group cannot be repaired. If either component is found to be defective, it is essential that correct installation and calibration procedures are used when installing new parts.This Special Instruction describes the correct procedures for installation of a new 844241 Strain Sensor Group and the correct procedures for calibration of the load indicator system. This procedure must be followed whenever a new 844241 Strain Sensor Group or 838843 Display Unit is installed.Do not perform any procedure, outlined in this publication, or order any parts until you read and understand the information contained within.Reference: Service Manual and Parts Manual.Strain Sensor Installation
A raised boom can fall causing injury or death if a hydraulic component fails.Install the boom lock or blocks before working under a raised boom.
The frame must be dry and at a minimum temperature of 15°C (59°F) shop temperature. Localized heating must not be applied to achieve this temperature.The strain sensor is bonded to steel mounting blocks which are welded to the left side of the machine frame, adjacent to the boom raise cylinder anchor.1. Disconnect the old strain sensor cable from the display unit cable (located under the dash panel), and remove the strain sensor.2. Clean the mounting blocks thoroughly, ensuring that all traces of adhesive are removed from the top faces.3. Use a straight edge and a 0.05 mm (0.002 in) feeler gauge to check the alignment of the top faces of the blocks. File the blocks if necessary until the top faces are aligned within 0.05 mm (0.002 in).4. Clean the screw holes by using an M8 tap. Be sure that the top faces of the mounting blocks are clean and dry. Degrease the mounting block faces.5. Route the new strain sensor cable to the dash panel housing and connect it to the display unit cable.
844241 Strain Sensor Group. (A) Transit plate. (B) Steel blocks.6. Disassemble the 844241 Strain Sensor Group and discard transit plate (A) and steel blocks (B). Remove the protective vinyl tape from the new strain sensor mounting faces, and degrease the mounting faces. Do Not scrape the mounting faces. The mounting faces are on the side of the sensor with the raised digits in the center.7. Apply a thin coating of 985214 Adhesive (Loctite 638®) to the faces of the mounting blocks and to the mounting faces of the sensor. The sensor is shown correctly installed in the following illustration.
Strain Sensor Installation.8. Install sensor (1) and tighten capscrews (2) hand tight only. Wait twenty minutes and then tighten the capscrews evenly, first to a torque of 20 N m (15 lb