This document is a repair manual for MAST REPAIR on various Hyster lift truck models. It provides detailed procedures for the removal, disassembly, cleaning, inspection, assembly, and installation of mast components, as well as adjustments and troubleshooting.
Function Description
The manual focuses on the mast assembly, which is a critical component of a lift truck responsible for lifting and lowering the operator platform and forks. It covers both two-stage and three-stage mast configurations. The mast system includes:
- Forks: The load-carrying attachments.
- Operator Platform: Where the operator stands to control the lift truck and access elevated areas.
- Mast Weldments: The structural frames (outer, intermediate, and inner masts) that guide the lifting components.
- Lift Cylinders: Hydraulic cylinders that provide the power for vertical movement.
- Lift Chains and Sheaves: Components that transmit force from the lift cylinders to the mast weldments and operator platform.
- Load Rollers and Strip Bearings: Guide and support the mast weldments during movement.
- Hydraulic System: Provides the necessary fluid power for lifting operations, including hoses, tubes, and control valves.
- Electrical System: Includes limit switches and wiring for control and safety.
The manual's primary function is to guide technicians through the repair process to ensure the mast operates safely and efficiently, maintaining the lift truck's lifting capabilities.
Important Technical Specifications
While specific dimensions and capacities are mentioned in the context of adjustments, the manual primarily focuses on procedural specifications rather than overall truck specifications. Key technical details include:
- Fork Alignment: Fork tips must be aligned within 3.2 mm (1/8 in.).
- Lift Chain Wear Limit: Chains must be replaced if they are 3% longer than a new chain (e.g., for a 254.0 mm (10.0 in.) new chain, the maximum length is 261.6 mm (10.3 in.)). A detailed table provides wear limits for various chain pitches.
- Mast Mounting Bolt Torque: Mast mounting bolts should be tightened to 225 N·m (166 lbf ft).
- Trunnion Cap Bolt Torque: Trunnion caps, bolts, and washers should be torqued to 203 N·m (150 lbf ft).
- Load Roller Clearance: Maximum clearance between the load roller and the mast weldment at the point of tightest fit is 0.8 mm (0.031 in.).
- Strip Bearing Clearance: Clearance should be less than 0.8 mm (0.031 in.) at the point of tightest fit.
- Operator Platform Load Roller Clearance: Clearance between the roller and the inner mast weldment at the point of tightest fit must be 0.1 to 0.8 mm (0.004 to 0.031 in.).
- Fork Height (Standard Lift Truck): Top of forks should be 76.2 ±6.35 mm (3.0 ±0.25 in.) above the floor in the fully lowered position.
- Fork Height (Furniture Lift Truck): Top of forks should be 165.1 ±9.525 mm (6.5 ±0.375 in.) above the floor in the fully lowered position.
- Lift System Leakage Rate: Maximum lowering rate due to internal leaks is 50 mm (2 in.) in 10 minutes at 32°C (90°F) hydraulic oil temperature, or 150 mm (6 in.) in 10 minutes at 71°C (160°F).
- Minimum Thread Engagement for Chain Anchor Nut: The minimum thread extending above the nut of the chain anchor is two times the chain pitch.
Usage Features
The manual outlines procedures for various Hyster lift truck models, including:
- R30XMF3 [A169]
- R30XMA3 [A185]
- N40-50EA, N40-45ER [C138]
- R30E/EA, R30EA-FS [D118]
- R30XMS2 [D174]
- R30XMS3 [E174]
- R30XM/XMA/XMF [F118]
- R30XM2, R30XMA2, R30XMF2 [G118]
- R30XM3 [H118]
Key usage features emphasized in the repair process include:
- Safety First: Extensive warnings are provided regarding heavy parts, hydraulic systems, electrical disconnections, and proper use of lifting mechanisms, blocks, and chains. Operators are warned never to work under a raised platform or forks without proper support.
- Systematic Disassembly/Assembly: Procedures are broken down into logical steps, often requiring specialized tools like cranes, slings, and pry bars.
- Shim Management: Importance of noting and maintaining shim arrangements during disassembly and assembly for correct component alignment and clearance.
- Hydraulic System Integrity: Instructions for capping hydraulic lines to prevent contamination and checking for leaks.
- Electrical System Handling: Disconnecting battery, carefully moving electrical cables, and connecting proximity switches.
- Chain Adjustment: Detailed steps for adjusting lift chains to ensure correct fork height and mast operation.
- Load Roller and Strip Bearing Adjustment: Procedures to ensure smooth movement and proper alignment of mast weldments.
Maintenance Features
The manual provides comprehensive maintenance-related information:
- Cleaning and Inspection: Detailed instructions for cleaning mast weldments, lift chains, sheaves, and load rollers using appropriate solvents and compressed air (with warnings against using steam or compressed air on sealed bearings).
- Wear Limits: Specific criteria for replacing worn components, particularly lift chains (3% elongation).
- Lubrication: Instructions to apply multipurpose grease to strip bearings, bearing, and roller surfaces of channels during assembly.
- Leak Checks: Procedures for checking both external and internal leaks in the hydraulic lift system, including maximum allowable lowering rates.
- Troubleshooting Guide: A table listing common problems (e.g., no movement, slow action, rough movement), possible causes (e.g., disconnected linkage, low oil, bad pump, bent rods, misalignment), and corresponding procedures or actions.
- Parts Replacement: Emphasis on using HYSTER APPROVED parts that meet or exceed original equipment manufacturer specifications.
- Periodic Maintenance References: Directs users to the "Operating Manual" or "Periodic Maintenance" sections (8000 SRM 924 or 8000 SRM 1472) for battery removal and general maintenance schedules.
- Wire Guidance System: Mentions specific installation procedures for trucks equipped with wire guidance (2200 SRM 1471).
The manual serves as a vital resource for maintaining the operational integrity and safety of Hyster lift truck masts.
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