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JAN 27, 2026

How the Thieman LRST-40 Level-Ride System Works: Platform Motion and Load Stability

The Thieman LRST-40 StowAway liftgate is a tuckunder liftgate engineered to keep the platform stable and level with the truck during loading and unloading. The model is rated at 4,000 lb capacity and uses a self-leveling mechanism to create a reliable, “level with truck” loading surface.

This article explains how that Level-Ride system works mechanically—focusing on the geometry of the cylinders, pivots, platform angle, and load placement—without covering operating steps, installation procedures, maintenance intervals, or troubleshooting.

• Documentation Resources from Thieman
• What is The Level-Ride System?
• How the Self-Leveling Mechanism Physically Works
• Platform Angle, Toe Adjustment, and Load Stabilization
• Load Positioning Requirements and Their Impact on Level-Ride
• Wear Points and Components That Influence Leveling Accuracy (Mechanical Effects Only)
• Why the LRST-40 Design Reduces Maintenance and Supports Consistent Leveling
• 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

What is The Level-Ride System?

Thieman describes the LRST-40 as a Level Ride Stowaway liftgate designed for loads up to 4,000 lb, featuring self-leveling action and an adjustable platform to provide a stable, “level with truck” surface for all types of loading conditions. The platform is a large 80" x 60" aluminum deck designed to support palletized freight and similar cargo.

Maintaining a level platform helps reduce the risk of pallets rolling or tipping and keeps cargo behavior predictable as it transitions between ground and bed height on the Thieman LRST-40 liftgate.

The Level-Ride system exists to keep the platform aligned with the truck and stable under rated loads, providing a consistent working surface for operators.

How the Self-Leveling Mechanism Physically Works

Movement Sequence During Raise and Lower

The Installation Manual states that the LRST is a self-leveling stowaway liftgate. The Owner’s Manual describes the core raise/lower behavior:

• When rising from the ground, the operator pushes the switch to UP; the platform levels, then raises off the ground.
• When lowering from bed height, the lift arms contact the ground first; holding the switch in DOWN causes the platform nose to tilt downward until it touches the ground.

This two-stage motion—initial leveling followed by vertical lift, and initial arm contact followed by controlled nose tilt—is the mechanical heart of the Level-Ride system.

Dual-Cylinder Geometry and Synchronized Motion

The LRST-40 uses dual lift cylinders as a standard feature to provide maximum stability. The brochure also highlights adjustable cylinder shafts for adjusting platform height, which gives installers a way to synchronize cylinder geometry.

Installation instructions specify that there must be 1.12 inches between the adjustable clevis and the cylinder barrel for each cylinder, and that both clevises must be adjusted the same. This ensures both cylinders operate through identical stroke lengths and leverage, which is critical to the platform’s ability to level itself rather than twist.

Pivot Points and Self-Lubricating Bearings

Thieman states that the LRST uses self-lubricating Teflon bearings at all of the LRST pivot points, with no lubrication required at those pivot points. The Owner's Manual further notes that many pivot points have special bushings that do not require lubrication but must be inspected regularly for wear.

Mechanically, these low-friction pivots allow the lift arms, idler arms, and platform hinges to move freely through the designed arc, so the platform can naturally rotate into a level attitude as the cylinders extend or retract.

Self-leveling on the LRST-40 is achieved by a combination of staged motion (level first, then lift), matched dual-cylinder geometry, and low-friction pivot bearings that allow the mechanism to move to its designed level position without operator correction.

Platform Angle, Toe Adjustment, and Load Stabilization

Platform Level and Toe Angle (Owner’s Manual)

In the Monthly Inspection and Maintenance section, Thieman specifies that when the truck is on level ground, and the platform is in its “leveled” and unloaded position, the entire load surface should be level or toed up at the ramp tip, so that when the usual load is placed on it, it becomes level under load. The same section notes that platform height relative to the spacer is corrected by adjusting the cylinder on the low side with a 15/16" wrench.

This slight upward toe at the ramp end is a deliberate design choice that compensates for deflection once cargo is on the platform.

Adjustable Cylinder Shafts as a Leveling Tool

The Installation Manual describes how the adjustable cylinder shafts are used to fine-tune the level and height:

• After the platform is checked to be level with the bed, the installer turns the cylinder shaft into the clevis one additional turn and then tightens the set screw.

This adjustment keeps both cylinders synchronized and maintains consistent platform height at the spacer over time.

How Toe Angle Affects Load Behavior

By setting the platform to be level or slightly toed up when unloaded, the design ensures that typical loads settle into an essentially level condition, rather than rolling outward toward the nose. This directly supports the stable operation of this tuck under liftgate, particularly when handling wheeled or palletized cargo within the LRST-40’s rated capacity.

Toe angle and cylinder-shaft adjustments give the LRST-40’s Level-Ride system a precise starting geometry so that, under normal loading, the platform naturally maintains a stable, level surface.

Load Positioning Requirements and Their Impact on Level-Ride

Off-Center Loading and Warnings

The Owner’s Manual makes several explicit warnings about load placement:

• The liftgate must not be overloaded, with the LRST-40’s standard maximum rated capacity listed as 4,000 lb.
• Operators must never off-center the load on the platform from side to side or away from the truck, because this may overload the liftgate.
• The center of weight of the load should never be placed beyond the center of the platform load surface away from the truck, and loads should be placed close to the platform edge nearest the truck.
• The manual states that, on the LRST model, off-center loading away from the truck may cause the nose of the platform to tilt downward severely when lowering from bed level, increasing the risk of falling loads.

These warnings are illustrated in the diagrams on page 8, which show correct centered loading versus incorrect off-center and forward-biased loading.

How Uneven Loads Affect the Level-Ride Mechanism

Because the Level-Ride system depends on equal reaction through both lift arms and cylinders, a side- or forward-biased load changes the forces acting on the pivot structure:

• One side of the mechanism carries more load, causing uneven arm rotation.
• The platform may attempt to follow its designed level path but is forced into a twist or early nose tilt, especially when lowering.

The warning note in the manual specifically directs operators to stop lowering and re-center the load if the platform begins to tilt downward while lowering, underscoring the connection between load position and leveling behavior.

Correct load positioning—centered and close to the truck—is fundamental to allowing the LRST-40 Level-Ride system to behave as designed. Off-center loading defeats the geometry and can produce unexpected tilting despite the self-leveling design.

Wear Points and Components That Influence Leveling Accuracy (Mechanical Effects Only)

Pivot Bushings and the 1/32" Wear Limit

The Owner’s Manual instructs that for bushed pivots, if the gap between pin and bushing exceeds 1/32 inch, the bushing should be replaced; for unbushed pivots, worn components should be replaced if the gap between pin and pivot exceeds 1/32 inch.

Mechanically, this tolerance keeps pivot centers close to their design locations. Excessive clearance allows relative motion between parts, which:

• Slightly changes the effective arm lengths and pivot angles.
• Introduces play that can make the platform settle at a slightly different angle side to side.

Because leveling depends on repeatable pivot geometry, staying within this 1/32" clearance is important for maintaining accurate Level-Ride behavior.

Cylinder Bypass and Drift (Conceptual Effect Only)

In the troubleshooting section, Thieman notes that bypassing cylinders will cause increased hydraulic drift and specifies a maximum allowable drift of 0.19 inch per hour for the LRST-40 platform.

From a purely mechanical standpoint, internal bypass reduces the effective holding force on that cylinder. When one cylinder bleeds pressure internally faster than the other, the supported side of the platform can slowly lower, creating a small but measurable tilt over time. This is why symmetric cylinder performance is important to the long-term accuracy of the Level-Ride system.

Tight pivot clearances and healthy, non-bypassing cylinders are key mechanical factors that preserve the LRST-40’s ability to hold and repeat its designed level geometry.

Why the LRST-40 Design Reduces Maintenance and Supports Consistent Leveling

Retracted Cylinder Rods During Transit

The brochure explains that the LRST has a unique design so that cylinder rods are retracted during transit to protect them from road debris. Retracted rods are less exposed to impact and contamination, helping preserve the surface finish and seals that control cylinder motion.

Weather-Protected Pump Enclosure

A plastic pump enclosure is standard on the LRST-40; it protects the power unit from the weather. Stable hydraulic components and electronics contribute to consistent pressure and flow, which support repeatable platform movement.

Self-Lubricating Bearings and Pivot Design

The same brochure notes that Teflon composite bearings with stress-proof pins are used for virtually maintenance-free operation at pivot points, and that no lubrication is required there. This keeps pivot friction low without constant greasing, which in turn helps the mechanism follow the intended leveling path under load.

Additional Supporting Features

The LRST-40 liftgate is also described as having dual lift cylinders, a heavy-duty lift frame, a snubber kit to reduce movement in the travel position, power up/power down operation, and an electrical design that meets TMC guidelines. All of these features contribute to the predictable, consistent performance of the Level-Ride system in service.

Design choices such as retracted rods, a weather-protected pump, and self-lubricating bearings reduce wear and variability in the mechanism, which directly helps the LRST-40 maintain its level-with-truck behavior across its service life.

Conclusion

The Thieman LRST-40 Level-Ride system combines controlled motion sequencing, dual-cylinder geometry, low-friction pivots, precise platform angle adjustment, and strict load positioning rules to keep the platform stable and level with the truck. When those design elements are respected in setup and use, this tuck under liftgate provides a predictable surface for moving freight within its 4,000 lb rating.

For support selecting tuck under liftgate parts, specifying OEM liftgate parts, or sourcing a tuck under liftgate for sale appropriate to your fleet, contact the LiftGateMe team for assistance based on OEM documentation.