This document is a service manual for Lift-Tek's 35DV/45DV/55DV-MQ Four Stage Full Freelift Mast. It provides comprehensive instructions for installation, periodic maintenance, troubleshooting, and service procedures for the mast, which is a critical component of material handling equipment, typically forklifts.
Function Description
The Lift-Tek mast is a multi-stage, full freelift mast designed to provide vertical lifting and lowering capabilities for loads. The "Four Stage" designation indicates that the mast consists of four telescoping sections (uprights) that extend to achieve the desired lift height. "Full Freelift" refers to the mast's ability to lift a load a certain distance without the inner mast sections extending, which is particularly useful in low-headroom environments like containers or trailers. The mast utilizes hydraulic cylinders and chains to achieve its lifting and lowering functions, controlled by the truck's hydraulic system.
Important Technical Specifications
The manual covers three specific models: 35DV, 45DV, and 55DV-MQ, implying variations in lifting capacity or other performance characteristics, though specific load capacities are not detailed in the provided excerpts.
Mast Components:
- Uprights: The mast consists of outer, inner intermediate, and inner uprights that telescope.
- Carriage: The component that carries the forks and moves vertically along the mast. It includes load rollers and thrust rollers for smooth movement.
- Cylinders:
- Main Lift Cylinders: These are single-stage piston-type cylinders responsible for the primary lifting action of the inner intermediate and inner uprights.
- Free Lift Cylinders: These are single-stage piston-type cylinders that provide the initial "freelift" by lifting the carriage without extending the mast uprights.
- Chains: Multiple chains are used for lifting, including main lift chains and freelift chains, which are critical for transmitting the lifting force from the cylinders to the carriage and uprights.
- Hoses: Hydraulic hoses connect the cylinders to the truck's hydraulic system, allowing for fluid flow to actuate the lifting and lowering.
- Mounting Bracket: The mast is mounted to the truck using a mounting bracket, which must be correctly installed and torqued.
Hydraulic System:
- The system uses hydraulic fluid to actuate the cylinders. The manual specifies SAE 40 wt. oil or Bowmar Heavy Load Red Grease for chain lubrication. For hydraulic oil, it recommends MIL-O-5606 or MIL-O-2104 petroleum base oil. If fire-resistant hydraulic oil is used, Lift-Tek must be contacted.
- Relief pressure for the hydraulic system is specified as 2600 psi, with a hose fitting size of 3/4 in. SAE O-ring and a hose size of No. 8 min. 13/32 in. Orifice.
Fasteners and Torque Specifications:
- Capscrews for various components have specific torque requirements, e.g., crosshead coverplate capscrew to 52 ft-lbs (71 Nm), inner intermediate upright capscrew to 81-88 ft-lbs (110-120 Nm), retainer capscrews to 26-30 ft-lbs (35-40 Nm).
- Cylinder retainer torque: 200-220 ft-lbs (270-298 Nm) for main lift cylinders, 95-125 ft-lbs (129-169 Nm) for freelift cylinders.
Usage Features
The manual primarily focuses on maintenance and service rather than operational use. However, it implicitly highlights features that contribute to the mast's functionality:
- Telescoping Uprights: The multi-stage design allows for significant lift heights while maintaining a compact retracted height.
- Full Freelift Capability: Enables lifting in confined spaces without increasing overall mast height.
- Robust Construction: The emphasis on proper installation, lubrication, and inspection suggests a design intended for heavy-duty use in industrial environments.
- Modular Design: Components like cylinders and uprights can be removed and serviced individually, facilitating repair.
Maintenance Features
The service manual outlines extensive maintenance procedures to ensure the mast's safe and reliable operation.
Installation:
- Mounting Bracket Installation: Detailed steps for installing the mounting bracket to the truck, including torque specifications for fasteners.
- Mast Installation: Instructions for lubricating bearing surfaces, attaching the mast to the truck, connecting hydraulic hoses, and checking hydraulic fluid levels.
- Internal Reeving: Comprehensive instructions for routing hydraulic hoses and chains through the mast uprights, ensuring proper clearances and tension.
Periodic Maintenance (Section 3):
- Daily Inspection: Visual inspection of the mast for any damage, loose components, or leaks.
- 100-Hour Inspection: More detailed inspection including lubrication of chains, checking for wear and damage, and inspecting thrust plugs/blocks.
- 500-Hour Inspection: Includes measuring load roller clearances, inspecting thrust plug/block clearances, checking chains for wear and stretch, and tightening backrest capscrews.
Service Procedures (Section 5):
- Mast Removal: Steps for safely removing the mast from the truck, including disconnecting hydraulic hoses and chains.
- Cylinder Service:
- Main Lift Cylinder Removal/Service: Instructions for removing cylinders from the mast (both on floor and on truck), disassembling, inspecting components (rod end, piston, seals, O-rings, etc.), and reassembling. Specific attention is given to proper seal installation and lubrication.
- Free Lift Cylinder Removal/Service: Similar detailed procedures for freelift cylinders.
- Cylinder Operation: Explains the hydraulic principles behind cylinder raising and lowering.
- Valve Cartridge Service: Procedures for lowering the mast and replacing valve cartridges.
- Carriage Service:
- Carriage Removal: Instructions for removing the carriage from the mast (both on truck and on floor).
- Carriage Inspection: Checks for excessive wear or damage on rollers, welds, and stub shafts.
- Mast Uprights Service:
- Upright Disassembly: Detailed steps for disassembling the uprights, including removing chains, cylinders, and rollers.
- Upright Inspection: Checks for wear, cracks, and damage on upright rails, load roller stub shafts, and thrust plugs/blocks.
- Upright Reassembly: Instructions for reassembling the uprights, including proper shimming for roller and thrust plug/block clearances, and reeving chains and hoses.
- Mast Skewing Adjustment: Procedure for extending the mast to full lift height and adjusting shims to ensure the mast is plumb and operates smoothly.
- Chains Service:
- Chain Lubrication: Emphasizes the importance of proper lubrication to prevent wear and corrosion.
- Upright and Carriage Position, Chain Tension: Instructions for checking and adjusting chain tension.
- Channel Lubrication: Lubrication of upright channels.
- Chain Inspection: Detailed checks for cracked side plates, tight pin joints, peened plate edges, protruding pins, turned pins, and overall wear/damage.
- Measuring Chain Stretch: Instructions for using a chain wear scale to determine if chains need replacement.
- Outer and Inner Main Lift Chain Adjustment/Replacement: Procedures for adjusting and replacing main lift chains.
- Free Lift Chain Adjustment/Replacement: Procedures for adjusting and replacing freelift chains.
Safety Warnings:
The manual includes numerous "WARNING" and "CAUTION" statements throughout, highlighting critical safety precautions, such as:
- Not standing on or near the mast while it is suspended by an overhead hoist.
- Ensuring proper support when working under the mast.
- Using correct brackets and crossmembers to prevent structural failure during installation.
- Contacting Lift-Tek if fire-resistant hydraulic oil is used.
- Not scratching seal grooves during cylinder service.
- Avoiding damage to the cylinder thread relief chamfer.
- The upright must be supported by a block to avoid possible injury during mast skewing adjustment.
- The inner intermediate upright must be supported by blocks to avoid possible injury during carriage removal.
This comprehensive manual ensures that technicians have all the necessary information to install, maintain, and repair the Lift-Tek 35DV/45DV/55DV-MQ Four Stage Full Freelift Mast, promoting safe and efficient operation of the associated material handling equipment.
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