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JAN 20, 2026

How to Maintain the Thieman LRST-40 Tuck Under Liftgate: Monthly and Semi-Annual Requirements

Proper service is essential for maintaining the safety, reliability, and performance of the Thieman LRST-40 tuck under liftgate. Thieman provides explicit maintenance intervals and inspection requirements that fleet operators must follow to prevent component wear, hydraulic issues, and unsafe operating conditions.

This guide summarizes those factory-defined requirements based entirely on the official LRST-40 Owner’s Manual, Installation Manual, and Brochure.

• Documentation Resources from Thieman
• Why is Maintenance Important?
• Monthly Inspection Checklist
• Semi-Annual Maintenance Requirements
• Hydraulic System Service Requirements
• Pivot Points, Bearings, and Spring Assemblies
• Decal Maintenance Requirements
• Conclusion

Documentation Resources from Thieman

Information in this article is sourced from Thieman LRST-40 manuals and technical guides as well as our team’s expertise. Always refer to your specific liftgate’s manuals for complete procedures and serial number, model, and year-specific details.

Reference PDFs used:

• Thieman LRST-40 Owners Manual
• Thieman LRST-40 Installation Manual
• Thieman LRST-40 Brochure

Why is Maintenance Important?

Thieman emphasizes that proper maintenance is critical to safe operation. The LRST-40 is designed with features that aid long-term durability—such as self-lubricating Teflon bearings, a plastic pump enclosure (protects the power unit from weather), and retracted cylinder rods during transit—but these features still require regular inspection and servicing. Following the factory maintenance schedule ensures that pivot wear, hydraulic contamination, structural cracks, and decal deterioration are identified early before they become safety concerns.

Correct maintenance also supports stable platform operation, extending equipment life and preventing unplanned downtime for vehicles that rely on the LRST-40 for daily loading operations.

Monthly Inspection Checklist

Monthly inspections verify the condition of all hydraulic, mechanical, structural, and safety components. Thieman requires operating the liftgate through its full cycle before beginning inspection. (Owners Manual, pp.10–11)

Platform Levelness and Height

• Confirm the platform is level—or slightly “toed up” at the ramp tip—when unloaded. This ensures it becomes level under load. (Owners Manual, p.10 )
• Check the platform height relative to the spacer. If one side sits lower, adjust the low-side cylinder using a 15/16" wrench. (Owners Manual, p.10 )

Structural Condition and Welds

Inspect for visible structural damage, including:

• Bent or distorted liftgate members
• Cracked welds
• Any deformation caused by overloading or abuse

(Owners Manual, p.10 )

Pivot Wear: The 1/32-Inch Threshold

Thieman defines strict pivot wear limits:

• Bushing pivots: Replace the bushing when the gap between the pin and the bushing exceeds 1/32"
• Non-bushed pivots: Replace worn components if the gap between the pin and pivot exceeds 1/32"  (Owners Manual, p.10 )

Required inspection locations include:

• Platform hinge shoulder bolts, pins, and bushings
• Cylinder pins and bushings
• Liftarm and idler arm pivots at the trunnion and platform
• Kicker arm pins and bushings
• Stow pins and nylon pads
• Rear impact guard pins/bushings (if installed) (Owners Manual, pp.10–11 )

Snubber Compression in the Stored Position

Snubbers should be slightly compressed when the platform is fully stowed. If not, they must be relocated or replaced (Owners Manual, p.11 ).

Improper snubber installation increases wear during vehicle transit.

Hardware, Guards, and Finish Condition

Verify that:

• All pins, bolts, and retainers are present and properly secured (Owners Manual, p.11).
• Protective covers and guards are installed and fastened (Owners Manual, p.11).
• Painted surfaces are intact; repair rusted finishes or replace corroded components (Owners Manual, p.11).
• Between dissimilar metals, use Eck—not abrasive anti-seize compounds—to prevent galvanic corrosion (Owners Manual, p.11).

Hydraulic and Electrical System Checks

Inspect hydraulic components for:

• Cylinder leaks
• Hose wear or cracking (replace as needed)
• Fitting leaks (tighten or replace) (Owners Manual, p.11 )

Check the hydraulic reservoir:

• With the liftgate stowed, fluid must be within 1/2" of the top of the reservoir (Owners Manual, p.11 ).

Electrical system inspection:

• All wiring and battery cable connections must be tight and corrosion-free (Owners Manual, p.11 ).

These monthly tasks allow operators to catch worn pivots, declining hydraulic performance, loose hardware, and corrosion issues early—before they affect liftgate safety or load stability.

Semi-Annual Maintenance Requirements

Semi-annual maintenance involves deeper mechanical and hydraulic servicing that supplements the monthly checklist.

This service interval focuses on motor integrity, corrosion control, and hydraulic system cleanliness, which are essential to the long-term reliability of the Thieman LRST-40. (Owners Manual, p.12)

Corrosion Prevention and Repainting

Repaint original painted components to prevent rust or corrosion from compromising structural integrity (Owners Manual, p.12 ).

Pump Motor Service Steps

Thieman specifies a detailed inspection process:

• Disconnect the battery cable
• Remove motor end cover
• Inspect brushes — replace if shorter than 1/8"
• Clean residue from the motor housing
• Lubricate armature-shaft bearing with light machine oil
• Reassemble (Owners Manual, p.12 )

Exceeding these limits can overheat the motor, gear pump, motor start solenoid, and valve coils, and may cause immediate component damage in severe cases.

Operators should track how frequently the lift is cycled—especially during back-to-back stops. Adhering to the 5-cycles/10-minute and 10% duty cycle rules keeps the hydraulic power unit within its thermal design range and extends the life of critical liftgate parts.

Hydraulic System Flushing and Reservoir Cleaning

If the hydraulic oil is dirty:

• Fully retract cylinders and support platform with a lift truck or crane
• Drain oil and flush the system
• Remove the reservoir and clean the suction line filter and interior
• Refill with approved hydraulic fluid (Owners Manual, p.12 )

Semi-annual service prevents premature motor wear, removes contaminated oil, and protects structural components, keeping the LRST-40 in safe working condition.

Hydraulic System Service Requirements

Hydraulic system performance determines lifting speed, load-handling capability, and cycling consistency.

Thieman specifies exact fluid types, temperature ranges, and operating limits that must be met to keep the LRST-40 functioning as designed. (Owners Manual, p.11)

Approved Hydraulic Fluids & Operating Temperature Ranges

Per the Hydraulic Fluid Chart (Owners Manual, p.11 ):

• Mobil Univis HVI-26: −45°F to 155°F
• Dexron VI / Dexron III: 0°F to 140°F
• Mobil 1 Synthetic ATF
• Shell Spirax S6 ATF X
• AeroShell Fluid 41 / Mobil Aero HF / Mobil Univis HVI-13 / MIL-PRF-5606J: −55°F to 100°F

Choosing fluid based on ambient temperature ensures consistent viscosity and pump performance.

System Relief Pressure and Maximum Electrical Load

Thieman specifies the following:

• Relief Pressure: 265 psi
• Max Amp Draw: 255 amps (Owners Manual, p.11 )

If relief pressure cannot be achieved or amp draw is excessive, hydraulic or electrical components require service.

Maintaining correct fluid type, pressure settings, and electrical load ensures stable and predictable platform performance under all rated load conditions.

Pivot Points, Bearings, and Spring Assemblies

The LRST-40 incorporates pivot bushings, Teflon composite bearings, and torsion springs, each with unique maintenance requirements.

While teflon bearings eliminate routine greasing, all pivot and spring components must still be inspected for wear, properly lubricated where required, and correctly operated.

Teflon Bearings Requiring No Lubrication

The LRST-40 uses self-lubricating Teflon composite bearings that provide “virtually maintenance-free operation at pivot points” (Brochure, p.2 ).

The Owner’s Manual adds:

• “Many pivot points…have special bushings which do not require lubrication, but must be inspected regularly for wear.” (Owners Manual, p.11 )

Bushing Replacement Requirements

Replace bushings or components whenever:

• The gap between the pin and the bushing exceeds 1/32 inch, or
• The gap between the pin and the non-bushed pivot exceeds 1/32 inch (Owners Manual, p.10)

Torsion Spring Lubrication and Service

The LRST-40 platform uses torsion springs to assist folding and unfolding. Thieman’s lubrication guidance includes:

• Lubricating across the coils of the platform springs so they can slide freely during operation (Owners Manual, pp.12, 25 ).
• Springs that make the platform harder to fold may be either dry or worn; lack of lubrication can increase folding force (Owners Manual, p.25).
• Replace platform torsion springs if broken or permanently deformed and no longer returning to their original position (Owners Manual, p.25).

Although the LRST-40 is engineered to reduce lubrication needs, operators must still inspect for wear and lubricate torsion springs appropriately to maintain safe platform folding geometry.

Decal Maintenance Requirements

Decals provide critical safety, capacity, and operating information.

Missing or illegible decals compromise operator safety and violate Thieman’s maintenance requirements. (Owners Manual, p.13)

Required LRST-40 Safety and Instructional Decals

The Owner’s Manual lists all mandatory decals and part numbers (Owners Manual, p.13 ):

• Warning – Off-Center Loading
• PTO / Fast Idle
• Danger – No Riding
• Operating Instructions
• Capacity – 4000 lb
• Warning – Keep Hands Clear
• General Warnings
• Working Area
• Use Handle
• Warning – High Pressure
• Wiring Diagram
• Reflectors (three required)

Thieman states:
“Replace any decals which are missing or not fully legible. DO NOT operate liftgate unless all decals are legible and properly located.” (Owners Manual, p.13 )

Keeping decals intact ensures operators receive critical hazard and usage information. Replacing worn or missing decals is a required maintenance task—not optional.

Conclusion

By following the factory-defined inspection schedule, operators ensure the LRST-40 tuck-under liftgate remains structurally sound, hydraulically stable, and safe to use. Monthly inspections identify early wear, hydraulic leaks, and component misalignment, while semi-annual servicing supports long-term reliability of the pump motor, hydraulic system, and structural components. Maintaining proper hydraulic fluid, performing regular pivot wear checks, and replacing decals all contribute to safe operation of the Thieman LRST-40 liftgate.

For OEM liftgate parts, decal replacements, or support interpreting the maintenance procedures, contact the LiftGateMe team for assistance.