Trailer Ramp Assistance / Single Spring System
CB100S72S Ramp Door Spring Kit - Single Spring 100 lb Assist with 72" Tube
Single-spring torsion ramp assist kit for enclosed trailer ramp doors. Designed to help counterbalance the ramp door when properly installed, adjusted, and matched to the trailer door weight.
Part Number: CB100S72S 100 lb Assist Rating 72" Tube
Overview
This R&P Carriages CB100S72S ramp door spring kit is a single torsion spring assist system for enclosed trailer ramp doors. The kit is intended for ramp-style rear doors where the spring rating, tube length, mounting layout, cable routing, and door weight match the application. When correctly installed and wound, the spring system helps reduce the lifting effort required to raise the ramp door and helps control door movement during normal operation.
R&P Service Insight
Ramp door spring systems are high-tension service components. Correct spring orientation, winding direction, and cable routing are critical to safe operation.
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Inside-Looking-Out Orientation: The installation manual states that, standing inside the trailer looking out, the black cable drum should be on the left-hand side.
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Wind Down, Not Up: The manual specifies that the spring should be wound down by pulling the winding bars, not pushing them.
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Use Proper Winding Bars: The manual calls for 1/2" diameter bars and recommends approximately 18" length for winding.
R&P Knowledge Hub
Compatibility: Intended for enclosed trailer ramp door spring assist applications where the 72" tube length, 100 lb spring rating, brackets, drums, and cable layout match the trailer.
Vehicle / System Fit: Trailer rear ramp door torsion spring assist system.
Installation Notes: The manual notes that cable mounting brackets should position the cable so it lines up with the outside edge of the door frame, and the cable should spool properly on the drum without rubbing.
Performance Insight: The manual states each spring is calculated by springing weight at ten full turns per spring, with door weight varying within a limited range. Proper balance must be verified after winding.
Brand & Fitment Note
Selling Brand: R&P Carriages
Application Reference: Any trailer or platform names in this listing describe compatibility, fitment target, or application style only where measurements, mounting points, and configuration match.
What This Means: This listing is for a R&P Carriages ramp door spring assist kit, not a guaranteed OEM-branded item unless specifically stated and verified.
Before Ordering: Verify ramp door weight, rear opening width, mounting space, tube length, cable path, drum orientation, and included components before installation.
R&P Repair Insight
The installation manual gives several checks that matter during replacement or first-time installation. These are not just setup details; they affect whether the door balances correctly and whether the cable tracks safely on the drums.
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Cable Path Check: Cables should travel down the back of the cable drum and through the door opening to the door attachment point. They should not cross the front of the cable drums.
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Winding Direction Check: The spring should grow in length when wound. If it grows in diameter, it is being wound backward.
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Cover Timing Check: The manual cautions that the set screw cover should be installed only after the spring is wound and the door has been tested for proper balance.
Features
Single Spring Ramp Assist Design
Designed as a single torsion spring system for enclosed trailer ramp door assistance.
100 lb Assist Rating
Listed as a 100 lb assist spring kit for matching ramp door applications.
72" Tube Length
Includes a 72" tube configuration for compatible trailer rear ramp door installations.
Manual-Guided Setup Notes
Installation guidance covers drum orientation, winding direction, cable routing, door balance checks, and set screw cover installation timing.
Specifications
| Specification |
Detail |
| Part Number |
CB100S72S |
| Brand |
R&P Carriages |
| Product Type |
Ramp door spring assist kit |
| Spring Style |
Single torsion spring system |
| Assist Rating |
100 lb |
| Tube Length |
72" |
| Application |
Enclosed trailer rear ramp door spring assist system |
| Installation Reference |
CB100S72S installation manual |
Fitment / Application
| Category |
Details |
| Vehicle / System |
Enclosed trailer ramp door spring assist system |
| Primary Fit |
Ramp doors requiring a 100 lb single-spring assist kit with a 72" tube |
| Orientation Note |
Manual states black cable drum should be on the left when standing inside the trailer looking out. |
| Winding Note |
Manual states the spring should be wound down and should grow in length as it is wound. |
| Notes |
Verify ramp door weight, mounting bracket location, cable alignment, door balance, and trailer structure before ordering or installing. |
Included Components
| Quantity |
Item |
| 1 |
Single torsion spring / 72" tube ramp assist assembly |
| 2 |
Cable drums |
| 2 |
Mounting brackets |
| 2 |
Lift cables |
| 1 |
Set screw cover |
| Included |
Additional small installation hardware shown with product; verify contents against current product photos before installation. |
Important Installation Warning: Torsion springs are under high tension and can cause serious injury if handled incorrectly. The installation manual recommends prior experience with torsion springs or professional installation. Use proper winding bars, keep control of the spring system while adjusting tension, inspect cables for fraying, and test the door for proper balance before installing the set screw cover. Do not exceed the manual’s stated winding limits, and verify all fitment and included components before installation.
Installation Manual Available
Review the CB100S72S manual before installation for winding direction, drum orientation, cable routing, balance testing, and set screw cover instructions.
PDF View Manual
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