Installation Method of 24V Starter Solenoid Switch for Liugong/Longgong Loaders and Forklifts (Including Precautions + Authoritative Sources)

I. Pre-installation Preparation (Safety + Tools + Spare Parts)

1. Safety and Power-off (Mandatory)

• Disconnect the negative terminal of the 24V battery (disconnect negative first then positive to prevent short-circuit sparking). Remove the starter assembly (if only replacing the switch, on-machine operation is allowed but removing the assembly is more recommended).

• Wear insulating gloves and goggles; insulate tools. Ensure the working area is well-ventilated and keep away from fire sources.

2. Tools and Spare Parts

• Tools: Socket/wrench set (commonly used sizes: 10/12/13/14mm), torque wrench, flathead/Phillips screwdriver, needle-nose pliers, multimeter, sandpaper/rust remover, lubricating grease (lithium-based grease/starter-specific grease), copper wire terminals, insulating tape/heat-shrink tubing.

• Spare Parts: Original or compatible 24V solenoid switch (Liugong/Longgong model-specific; verify shift fork ejector rod length, mounting hole spacing, and terminal specifications), O-rings/gaskets, fixing bolts, springs, lock washers (replace if old parts are worn).

3. Pre-treatment

• Clean the starter mating surface, solenoid switch mounting surface, and terminals to remove oil stains, rust, and oxide layers.

• Check the starter shift fork, overrunning clutch, drive gear, and armature shaft for jamming, wear, and looseness.

• Pre-inspection of the new switch: Use a multimeter to measure the pull-in coil/hold coil resistance (24V standard: pull-in coil ≈ 0.5–1Ω, hold coil ≈ 3–5Ω; discard immediately if short-circuited or open-circuited). Manually press the ejector rod to ensure smooth extension and retraction without jamming.

II. Step-by-Step Installation Procedures (Two Methods: On-machine or Assembly Removal; Assembly Removal Recommended)

Method A: Installation After Removing the Starter Assembly (Recommended, More Operating Space, Lower Failure Rate)

1. Remove the old solenoid switch

• Unscrew the 2–3 fixing bolts connecting the solenoid switch to the starter housing (common specifications: M6/M8, torque ≈ 8–12N·m).

• Disconnect the switch terminals: first remove the thick battery cable (main contact), then the control wire (pull-in coil small terminal), and mark the wire sequence.

• Separate the switch from the starter shift fork: the ejector rod and shift fork are mostly connected via hooks/slots; gently pry to separate and remove the old switch.

• Check the shift fork return spring and ejector rod bushing; replace if severely worn.

2. Pre-install and Align the New Switch

• Apply a small amount of lubricating grease to the contact surface of the switch ejector rod/shift fork (avoid over-greasing to prevent contact contamination).

• Clip the switch ejector rod into the shift fork slot/hook and ensure accurate alignment without deflection (deflection will cause improper meshing, gear teeth impact, and ejector rod breakage).

• Reinstall the O-ring/gasket, align with the mounting holes, and pre-tighten the fixing bolts (do not fully tighten).

3. Fastening and Wiring

• Tighten the fixing bolts to the original factory torque (Liugong/Longgong 24V starters: M6 ≈ 8–10N·m, M8 ≈ 12–15N·m).

• Wiring sequence: First connect the control wire (small terminal, key start signal), then the main contact thick wire (battery positive terminal, nut torque ≈ 6–10N·m).

• Add flat washers and spring washers to the terminals to prevent loosening. Cover exposed terminals with insulating sleeves or wrap with insulating tape to avoid ground short circuits.

4. Reinstall the Starter Assembly

• Clean the flywheel housing mating surface, reinstall the starter, and tighten the fixing bolts to a torque of ≈ 40–50N·m (Liugong/Longgong general specification).

• Reconnect the battery negative terminal and test: turn the key—the drive gear should smoothly mesh with the flywheel, retract quickly after startup, with no gear impact, abnormal noise, or smoke.

Method B: Direct On-machine Replacement (Emergency Use, Limited Space)

1. After power-off, mark and disconnect all wires, then loosen the switch fixing bolts.

2. Carefully separate the ejector rod from the shift fork (prevent the shift fork from falling into the flywheel housing).

3. Remove the old switch, install the new switch and align the ejector rod with the shift fork, then pre-tighten the bolts.

4. Complete wiring, fastening, and power-on testing following the same steps as Method A.

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Precautions for Installing 24V Starter Solenoid Switch of Liugong/Longgong Loaders and Forklifts

Standardized Power-off Operation

1. Before installation, disconnect the negative cable of the storage battery (for 24V systems, disconnect the negative connections of both battery packs). Live operation is strictly prohibited to prevent short-circuit sparking caused by tools touching the terminals.

2. Before power-on testing, reconfirm that all tools and debris are kept away from the starter and flywheel housing area.

Strict Matching of Models and Accessories

1. Must select original or equivalent 24V solenoid switches for corresponding Liugong/Longgong models, and check the key parameters: shift fork ejector rod length, mounting hole spacing, main contact current capacity, and terminal specifications (the thick wire terminal is for power input, and the thin wire terminal is for control signal).

2. 12V switches are strictly prohibited to replace 24V switches; otherwise, problems such as weak pull-in and overheating burnout of the coil will occur. Mismatched ejector rod length will lead to too deep or too shallow meshing between the drive gear and the flywheel, causing gear knocking failure.

Requirements for Alignment and Lubrication in Mechanical Assembly

1. The connection between the switch ejector rod and the starter shift fork must be accurately centered. For connections using clamping slots/hooks, ensure full engagement to avoid deflection; deflection will cause ejector rod bending, switch housing cracking, and improper meshing.

2. Apply a small amount of starter-specific lithium-based grease to the contact surface of the ejector rod and the shift fork, as well as the shift fork pin shaft. Over-greasing is strictly prohibited (grease entering the switch interior will contaminate the contacts and cause poor contact); it is forbidden to apply any grease to the internal contacts of the switch.

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References：

Authoritative Sources

I. Liugong Original Factory Authoritative Sources (Model-Specific)

1. Maintenance Manual for ZL50CN/855N Loaders (Published by Liugong Official)

• Source Chapters: Starter assembly disassembly and installation, solenoid switch replacement, torque specifications, wiring and insulation requirements, troubleshooting.

• Core Basis: 24V solenoid switch model matching, ejector rod alignment, fixing bolt/terminal torque, sealing and waterproofing requirements, step-by-step testing procedures.

2. Maintenance Manual for CLG Series Forklifts (e.g., CLG20/30/35) (Published by Liugong Official)

• Source Chapters: Electrical system - starter section, safety specifications for solenoid switch replacement, no-load/on-vehicle testing standards, requirements for synchronous inspection of associated components (shift fork, overrunning clutch).

II. Longgong Original Factory Authoritative Sources (Model-Specific)

1. Maintenance Manual for LG855/856 Loaders (Published by Longgong Official)

• Source Chapters: Starter solenoid switch disassembly and installation, 24V circuit safe operation, anti-loosening and insulation, fault diagnosis and elimination.

2. Maintenance Manual for FD Series Forklifts (e.g., FD30/35) (Published by Longgong Official)

• Source Chapters: Starter assembly maintenance, precautions for solenoid switch replacement, wiring sequence, replacement specifications for gaskets/O-rings.

III. National/Industry Standards (General Technical Specifications)

1. QC/T 29008-2016 Technical Specifications for Automotive Starters

• Core Basis: Starter solenoid switch coil resistance, contact performance, installation torque, insulation performance, no-load/load testing requirements, safe operation specifications.

2. QC/T 731-2005 Technical Specifications for Automotive Solenoid Switches

• Core Basis: Solenoid switch structure, assembly accuracy, ejector rod stroke, return performance, waterproof and dustproof properties, terminal anti-loosening and insulation requirements.

3. GB/T 19063-2009 Construction Machinery - Starters

• Core Basis: Installation, testing and fault judgment standards for solenoid switches of construction machinery-specific starters (including 24V), applicable to non-road machinery such as loaders and forklifts.

IV. Technical Specifications of Mainstream Supporting Manufacturers (Applicable to Liugong/Longgong Models)

1. Prestolite 24V Starter Solenoid Switch Installation Manual (Mainstream supporting product for Liugong/Longgong)

• Core Basis: Model matching, ejector rod and shift fork alignment, lubrication requirements, wiring sequence, no-load test duration (≤ 5 seconds per time), prohibited operations such as striking.

2. Bosch/Valeo 24V Starter Solenoid Switch Maintenance Manual

• Core Basis: Coil testing, contact maintenance, sealing and waterproofing, torque standards, requirements for synchronous inspection of associated components (carbon brushes, commutators, overrunning clutches).