Modular Open-End Wrench with Detachable Jaw Heads for Tight Spaces

The problem

Standard open-end wrenches have a fixed head welded or forged to the shank at a single angle. When a nut sits deep inside a hollow fixture, behind a sink basin, or next to protruding pipes, the fixed geometry prevents the jaws from reaching the fastener. Carrying a full set of fixed wrenches adds weight, yet none may fit the specific angle needed in a cramped installation cavity. According to the patent, the objective is a simple, portable, disassemblable structure that adapts to different nut sizes and narrow embedded positions.

The solution

1. The handle (12) features two distinct mounting points: a first installing hole (121) drilled through its sidewall for lateral torque, and a second installing hole formed inside a raised projection (123) at the handle’s end for axial alignment.
2. A connecting rod (11) carries square connection end blocks (111) at both its inner and outer ends. These blocks plug into the chosen handle hole and into the jaw head, connecting the parts detachably.
3. The fastener jaw (10) comes in multiple sizes—about seven specifications based on bayonet socket width. Two snap arms (101) stand perpendicular to the jaw body, creating an open bayonet socket that receives a nut or screw head.
4. For crowded pipe areas, an arc-shaped segment (102) jaw curves away from obstacles. For broken bolts inside hollow objects, a horizontal segment (104) jaw keeps the profile flat.
5. A tapered knob (122) with anti-slip veins sleeves over the handle to improve grip during manual turning.

Who it is for

• Plumbing hardware brands looking to add a specialized basin wrench alternative to their retail catalogs, targeting homeowners who struggle with faucet mounting nuts.
• Professional maintenance contractors servicing HVAC units, water heaters, and commercial restrooms where fasteners hide behind panels and inside tubular frames.
• Automotive aftermarket tool suppliers offering mechanics a compact kit for reaching suspension or engine bay nuts blocked by hoses and brackets.
• Industrial equipment manufacturers bundling a dedicated service tool with machinery that uses recessed fasteners in hollow structural members.

How it works

The main parts

Assembly and use steps

1. Select the jaw size matching the target nut or bolt head width from the available specifications.
2. Insert the rod’s outer end block (111) into the jaw’s connecting hole (103). The square shape connects them.
3. Choose the handle angle: plug the rod’s inner end block into the first installing hole (121) on the sidewall for lateral leverage, or into the projection’s hole (123) for straight-line access down a hollow tube. Adjust the insertion depth in the projection as needed.
4. Place the bayonet socket over the fastener until the snap arms (101) flank the nut.
5. Turn the handle to rotate the rod and jaw together, loosening or tightening the fastener.
6. Disassemble the three modules for storage or swap the jaw for a different size.

Applications

Under-sink faucet installation

Plumbers replacing single-cold or hot-and-cold taps must reach mounting nuts trapped between the basin bottom and the wall. The side-mounted rod provides the lateral swing needed in this shallow cavity, while the bayonet socket slides onto the nut without requiring vertical clearance above the threaded stud.

Hollow structural frame assembly

When assembling tubular metal furniture or roll cages, fasteners often sit inside the hollow profiles. Inserting the rod axially through the handle’s end projection allows the jaw to reach deep into the tube, and the adjustable insertion depth sets the exact reach required for each joint.

Broken bolt extraction in confined engines

A bolt snapped flush inside a blind hole leaves no room for standard pliers. The horizontal segment jaw keeps the tool profile minimal, sliding its snap arms over the remaining stub to apply extraction torque where bulkier tools collide with adjacent engine block castings.

Water heater element replacement

Heating elements secured by large flange nuts sit behind insulation jackets and wiring harnesses. Swapping to a larger jaw specification accommodates the wide nut, and the arc-shaped jaw curves around protruding pipes that would otherwise block a straight wrench head.

Appliance repair and maintenance

Washing machine pump housings and dishwasher circulation motors use fasteners tucked behind plastic shrouds. The modular nature lets technicians carry one handle and rod with several small jaws instead of a heavy ring spanner set, navigating tight appliance interiors efficiently.

Where it is less suitable

• High-torque automotive lug nuts - the detachable square blocks are designed for plumbing and light mechanical tasks, not the extreme forces required for wheel lug removal.
• Precision instrument calibration - the bayonet socket lacks the fine tolerance control of dedicated pin spanners used on optical or laboratory collars.
• Continuous production line use - pneumatic or electric drivers outperform manual modular wrenches for repetitive assembly tasks involving hundreds of identical fasteners daily.