Caldwell Model L Vertical Locking Lifting Clamp

Vertical Locking Lifting Clamp – Ergonomic 90° Plate Turning for Steel Fabrication

The Renfroe Model L is an ergonomic vertical locking lifting clamp designed for turning a single plate or structural member from horizontal to vertical and back to horizontal through the same 90° arc. Rated at 0.5 tons capacity, it is purpose-built for contractors and steel fabricators who need precise, controlled plate handling on the job site or in the shop. The clamp is manufactured by The Caldwell Group in Rockford, IL, under the trusted RENFROE brand, which has served international lifting clamp users for more than 50 years.

The Model L is a lighter-duty, more ergonomic alternative to the Model J, making it the preferred choice when ease of handling and operator comfort are priorities without sacrificing reliable vertical lifting performance. The "Lock Open – Lock Closed" locking feature sets it apart by making attachment and removal from the plate straightforward and secure.

Key Features & Benefits

Lock Open – Lock Closed Feature

The integrated locking mechanism allows the clamp to be positively locked in both the open and closed positions. This means the clamp stays open for easy placement onto the plate and locks closed before the lift begins, reducing the risk of accidental disengagement during operation.

90° Rotation Arc for Plate Turning

The Model L is specifically designed to turn a single plate or member from horizontal to vertical and back through the same 90° arc. This capability is essential in steel fabrication and structural assembly workflows where plates must be repositioned without additional rigging setups.

Ergonomic Design

Weighing just 4.8 lbs, the Model L is designed with operator ergonomics in mind. Its compact and lightweight construction reduces fatigue during repeated attachment and removal cycles, improving productivity over the course of a workday.

Single Plate Lifting

The Model L is rated and designed for lifting one plate at a time, ensuring load integrity and safe operation. This design prevents the accidental lifting of multiple plates, which is a critical safety consideration in vertical clamp applications.

Common Applications

Plate Turning in Steel Fabrication

The Model L excels at turning individual steel plates from horizontal to vertical orientation, a routine requirement in structural steel fabrication shops and on construction sites.

Vertical Lifting of Structural Members

The clamp is suited for lifting single plates or structural members vertically when the rigging force is directly above and in line with the lifting shackle.

Repositioning Plates During Assembly

When steel members need to be repositioned or flipped during structural assembly, the Model L provides a controlled, secure grip for safe repositioning through its 90° arc.

Compatible Materials

• Single steel plates
• Single structural steel members
• Flat plate stock (0 in. to 0.63 in. thickness range)

Product Documents

• Download Catalog
• Download Operator's Manual
• Lifting Clamp Survey Report
• Lifting Tool Inventory and Maintenance Form
• Minimum Recommended Clamp Inspections
• Renfroe Repair Kits Catalog

Application Instructions

Stage 1: Pre-Lift Inspection

1. Read and understand the Operator's Manual before using the clamp.
2. Inspect the clamp before each lift following the inspection and maintenance instructions in the manual.
3. Verify the plate thickness is within the rated range (0 in. to 0.63 in.) for the 0.5-ton Model L.
4. Confirm the load does not exceed the 0.5-ton rated capacity.
5. Ensure the load is secured before attaching the clamp.

Stage 2: Attaching the Clamp

1. Use the Lock Open feature to hold the clamp open for placement onto the plate edge.
2. Position the clamp on a single plate only — do not lift from the bottom of a plate stack.
3. Once seated on the plate, engage the Lock Closed feature to secure the clamp before lifting.
4. Do not lift with the lock in the open position.

Stage 3: Rigging and Lifting

1. Use a flexible connection between the crane hook and the clamp shackle — do not attach the clamp directly to the crane hook or use a heavy flexible connection.
2. Ensure the lifting force is directly above and in line with the lifting shackle for a vertical lift.
3. Use enough clamps to balance the load; do not lift unbalanced loads.
4. Do not lift over workers, safety areas, or personnel.
5. Do not side load with a straight shackle clamp.

Stage 4: Plate Turning Operation

1. During turning, ensure the edge of the plate opposite the clamped edge remains in contact with a supporting surface such as a factory floor.
2. Do not allow the load on the clamp to exceed the rated capacity during the turning operation.
3. Turn the plate through the 90° arc from horizontal to vertical, or return through the same arc.
4. Do not rush the turning operation.

Stage 5: Removing the Clamp

1. Once the plate is safely supported, use the Lock Open feature to release the clamp from the plate.
2. Inspect the clamp after use and follow maintenance instructions before storing.
3. Use only RENFROE replacement parts to ensure proper clamp operation if repairs are needed.
4. Do not grind, weld, or modify the clamp in any manner.

Technical Specifications

Safety Data Summary

Safe Handling

• Do not lift over workers, safety areas, or personnel.
• Do not lift with the lock in the open position — always lock closed before lifting.
• Do not use a connection that may release the clamp.
• Do not attach the clamp directly to the crane hook or use a heavy flexible connection; always use a flexible connection between the crane hook and clamp shackle.
• Use the correct clamp for the job; do not use large capacity clamps to lift light loads.
• Always operate within the rated 0.5-ton capacity; do not overload the clamp.
• Use enough clamps to balance the load; do not lift unbalanced loads.
• Do not side load with a straight shackle clamp.
• Do not lift more than one plate at a time with this vertical clamp.
• Do not lift a plate horizontally — this is a vertical lift clamp.
• Do not lift from the bottom of a plate stack.
• Do not alter, grind, weld, or modify the clamp in any manner.
• Secure the load before attaching the clamp.
• Always refer to the pre-lift inspection checklist in the Operator's Manual before each lift.
• Use only RENFROE replacement parts to ensure proper clamp operation.
• Consult the Operator's Manual or RENFROE when in doubt about any operation.

Frequently Asked Questions

Q: Can the Model L turn a plate from horizontal all the way to horizontal (180° total)?
A: Yes. The Model L can turn a single plate from horizontal to vertical and back to horizontal, completing a 180° total arc by moving through the same 90° arc twice.

Q: What is the maximum plate thickness this clamp can handle?
A: The Model L (0.5-ton model) accommodates plate thicknesses from 0 in. up to a maximum of 0.63 in.

Q: Can I lift more than one plate at a time with the Model L?
A: No. The Model L is designed and rated for lifting a single plate at a time. Lifting multiple plates simultaneously or lifting from the bottom of a plate stack is not permitted.

Q: What is the difference between the Model L and the Model J?
A: The Model L is described as a lighter-duty, more ergonomic version of the Model J. It is better suited for applications where ease of handling and operator comfort are priorities.

Q: Should I attach the clamp directly to the crane hook?
A: No. Always use a flexible connection between the crane hook and the clamp shackle. Direct attachment to the crane hook or use of a heavy flexible connection is not permitted.

Q: Can I modify or repair the clamp with non-OEM parts?
A: No. The clamp must not be ground, welded, or modified in any manner. Only RENFROE replacement parts should be used to ensure proper clamp operation and maintain safety.