Caldwell Model J Vertical Lifting Clamp – Locking Type

Renfroe Model J Vertical Lifting Clamp – Locking Type for Single Plate Turning

The Renfroe Model J is a vertical lifting clamp engineered to turn a single plate or member from horizontal to vertical and back to horizontal through the same 90° arc. Designed for contractors and rigging professionals who need reliable, repeatable plate handling on the job site or in a fabrication environment, the Model J delivers a 0.5-ton capacity in a compact, rugged package. Manufactured by The Caldwell Group in Rockford, IL, the Model J is part of the trusted RENFROE product line that has been the industry standard for vertical plate lifting for more than 50 years.

What sets the Model J apart from basic vertical lifting clamps is its integrated Lock Open – Lock Closed feature and its round swivel jaw design. While standard clamps lack a positive locking mechanism, the Model J locks positively in both the open and closed positions, allowing safe, controlled attachment and removal even in demanding field conditions.

Key Features & Benefits

90° Arc Plate Turning Capability

The Model J is purpose-built to turn a single plate or member from horizontal to vertical and back to horizontal through the same 90° arc. This eliminates the need for manual repositioning of the load mid-lift, saving time and reducing handling risk on structural steel and plate work.

Lock Open – Lock Closed Feature

The integrated Lock Open – Lock Closed mechanism allows the clamp to be positively secured in both the open and closed positions. This makes attaching and removing the clamp faster and safer, preventing accidental jaw movement during placement or release.

Round Swivel Jaw Design

The round swivel jaw clamp pivots when the lift is bumpy or uneven, preventing the plate from walking off the clamp during the lift. This self-adjusting feature is critical when working in environments where crane movement or load swing is unavoidable.

Proven Rugged Construction

The Model J is recognized as the industry standard for vertical plate lifting clamps, reflecting decades of real-world performance across heavy construction, steel fabrication, and rigging applications. Its robust body construction is designed to withstand the repeated stress of production lifting environments.

Compact and Lightweight Profile

At 10 lbs with an overall length of 12 inches, the Model J is easy to handle, attach, and transport without adding significant overhead to the rigging setup. The compact clamp body dimensions (5.62 in. H × 6.5 in. L × 3.25 in. W) allow it to work in tighter clearance conditions than larger capacity alternatives.

Common Applications

Structural Steel Plate Turning

The Model J is used to rotate flat steel plates from a horizontal storage or staging position to a vertical orientation for welding, fitting, or placement, and back again through the same 90° arc.

Single Member Handling

Ideal for lifting and repositioning a single structural member or plate where load control and consistent grip are required throughout the turn cycle.

Steel Fabrication Shops

Used in fabrication environments where plates must be repeatedly turned and oriented for welding or machining operations, the locking feature speeds up clamp attachment and removal between lifts.

Construction Site Rigging

Suitable for field rigging operations where plates or members need to be set vertically from flat delivery or staging positions, with the swivel jaw providing compensation for imperfect crane alignment.

Compatible Materials

• Steel plate (flat)
• Structural steel members
• Single plates up to 0.62 in. thickness (for this model variant)

Product Documents

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

Application Instructions

Before the Lift

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. Secure the load before attaching the clamp.
4. Verify the clamp model and capacity are correct for the load — do not use large capacity clamps to lift light loads, and do not exceed rated capacity.
5. Use a flexible connection between the crane hook and the clamp shackle. Do not attach the clamp directly to a crane hook or use a heavy flexible connection.

Attaching the Clamp

1. Use the Lock Open feature to hold the jaw open while attaching the clamp to the plate edge.
2. Verify the plate thickness falls within the clamp's rated range (0 to 0.62 in. for this model variant).
3. Engage the Lock Closed feature to positively lock the jaw closed before initiating the lift.
4. Do not lift with the lock in the open position.

During the Lift

1. Lift only a single plate at a time — do not lift more than one plate simultaneously with a vertical clamp.
2. Do not lift over workers, safety areas, or personnel.
3. During turning operations, the edge of the plate opposite the clamped edge should remain in contact with a supporting surface (such as a factory floor) and the load on the clamp must not exceed one half the rated capacity during the turn.
4. Do not rush the turning operation.
5. Do not side load with a straight shackle clamp.
6. Use enough clamps to balance the load — do not lift loads that are not balanced.

After the Lift

1. Use the Lock Open feature to safely release the clamp from the plate after the load is secured.
2. Inspect the clamp after use and follow maintenance instructions. Record condition using the Lifting Clamp Survey Report.
3. Use only genuine RENFROE replacement parts to ensure proper operation.
4. Do not alter, grind, weld, or modify the clamp in any manner.

Technical Specifications

Safety Data Summary

Hazard Information

• Do not lift over workers, safety areas, or personnel.
• Do not lift with the lock in the open position.
• Do not use a connection that may release the clamp.
• Do not attach the clamp directly to a crane hook or use a heavy flexible connection.
• Do not overload the clamp beyond its rated capacity.
• Do not lift more than one plate at a time with a vertical clamp.
• Do not lift plate horizontally with a vertical lift only clamp.
• Do not misuse the clamp (e.g., do not lift plate from the bottom of a plate stack).
• Do not side load with a straight shackle clamp.
• Do not alter, grind, weld, or modify the clamp in any manner.

Safe Handling

• Read and understand the Operator's Manual before using the clamp.
• Inspect the clamp before each lift and follow inspection and maintenance instructions.
• Use a flexible connection between the crane hook and the clamp shackle.
• Use the correct clamp for the job and within its rated capacity.
• Use enough clamps to balance the load.
• Secure the load before attaching the clamp.
• Use only genuine RENFROE replacement parts.
• During turning operations, keep the opposite plate edge in contact with a supporting surface and do not exceed one half rated capacity on the clamp during the turn.
• Consult the Operator's Manual or RENFROE when in doubt.
• Consider attending a RENFROE factory training class to establish proper clamp use.

Frequently Asked Questions

Q: Can the Model J turn a plate both from horizontal to vertical and from vertical back to horizontal?
A: Yes. The Model J is specifically designed to turn a single plate or member from horizontal to vertical and back to horizontal through the same 90° arc.

Q: What is the maximum plate thickness this model handles?
A: The 0.5-ton Model J (part number J-00.50-A) accepts plate thickness from 0 to 0.62 in. Other plate thickness ranges are available in alternative part numbers within the same capacity tier.

Q: What does the Lock Open – Lock Closed feature do?
A: The lock holds the jaw positively in both the open and closed positions. Lock Open allows easy attachment and removal of the clamp from the plate. Lock Closed secures the jaw during the lift. The clamp must never be lifted with the lock in the open position.

Q: Can I attach the Model J directly to a crane hook?
A: No. The Operator's Manual specifies that a flexible connection must be used between the crane hook and the clamp shackle. Direct attachment to a crane hook is not permitted.

Q: Can the Model J lift more than one plate at a time?
A: No. The Model J is a vertical clamp rated for lifting a single plate at a time. Lifting more than one plate simultaneously is not permitted.

Q: Are replacement parts available for the Model J?
A: Yes. RENFROE offers genuine replacement parts including components such as the lock assembly, cam assembly, swivel jaw, shackle, and associated pins and springs. Only genuine RENFROE replacement parts should be used to ensure proper operation. See the Renfroe Repair Kits Catalog linked above.