Doughty Clamps Explained: Which One Do You Need for Your Rig?

MTN Team·

Hook clamps, half couplers or Gravlock? This guide explains every Doughty clamp type, their load ratings and which to choose for your stage or studio setup.

Doughty Clamps Explained: Which One Do You Need for Your Rig?

If you have ever stood in front of a rigging hardware catalogue wondering whether you need a hook clamp, a half coupler, or something else entirely, you are not alone. Doughty Engineering makes one of the most comprehensive ranges of clamps in the entertainment industry, and choosing the right one for your specific application makes a real difference to how quickly and safely you can rig.

This guide covers every type of Doughty clamp available at MTN Shop, what each one is designed for, and how to choose the right one for your setup.

What is a Doughty Clamp?

A Doughty clamp is a rigging accessory used to attach lighting fixtures, speakers, cameras, or other equipment to a tube, bar, or truss. Doughty Engineering has been manufacturing clamps in the UK since 1985, and their range is used across theatre, film, television, concert touring, and broadcast studio environments.

All Doughty clamps are stamped with their Safe Working Load (SWL), which tells you the maximum weight the clamp can safely support. It is the figure you must work within to keep your rig compliant with LOLER (Lifting Operations and Lifting Equipment Regulations) and safe for everyone working beneath it.

Types of Doughty Clamps

Doughty Engineering offers a highly versatile selection of clamps designed to meet the rigorous demands of the entertainment industry. From lightweight studio setups to heavy-duty concert touring rigs, their range includes various styles, such as hook clamps, couplers, and specialized brackets, each engineered for specific tube diameters and weight capacities to ensure maximum safety and rigging efficiency.

Trigger Clamps and Quick Trigger Clamps

The trigger clamp combines the function of a hook clamp and a half coupler in a single tool. It allows one-person operation when rigging heavier fixtures, with a trigger mechanism that speeds up attachment without sacrificing grip.

The quick trigger clamp takes this further by mounting at any point on a truss piece without obstruction, thanks to the positioning of the knob. This is particularly useful when rigging on a busy truss where standard clamps cannot be fitted without removing adjacent fixtures.

Best for: Heavier fixtures that need faster rigging, busy truss sections where standard clamp access is limited, one-person rigging operations.

Trigger Clamps and Quick Trigger Clamps
Doughty 38-51mm Quick Trigger Clamp (TÜV approval) Doughty 38-51mm Quick Trigger Clamp (TÜV approval)£26.94 View Doughty 50mm Trigger Clamp Doughty 50mm Trigger Clamp£21.55 View

Hook Clamps (C Clamps)

Hook Clamps (C Clamps)

The hook clamp, also known as a C clamp, is the most traditional and widely used rigging accessory in stage lighting. It hooks over a truss or barrel, allowing a single technician to safely hang a fixture before securing its bolt. For standard theatre and event work, the 50mm medium-duty hook clamp is the industry benchmark, fitting 48-51mm bars with a Safe Working Load (SWL) of 100kg to cover the vast majority of conventional and LED luminaires.

When rigging heavier equipment that requires a higher weight capacity on the same bar diameters, the 50mm heavy-duty hook clamp is the ideal upgrade, stepping the SWL up to 150kg. Both options provide a highly reliable, cost-effective solution for everyday hanging needs without causing structural damage to your aluminum or steel tubes.

Best for: General theatre, studio, and event lighting. Hook clamps are the most affordable and straightforward option for most rigs.

Doughty 50mm Hook Clamp (Steel) - Medium Duty Doughty 50mm Hook Clamp (Steel) - Medium Duty£5.39 View Doughty 50mm Heavy Duty Hook Clamp (Steel) Doughty 50mm Heavy Duty Hook Clamp (Steel)£8.88 View

Atom Hook Clamps

The Atom Hook Clamp is the smallest clamp in the Doughty extruded aluminium range. Despite its compact size, it carries a Working Load Limit of 100kg and TUV approval. It fits tubes with exterior diameters of 25mm to 38mm, making it well suited to lightweight trusses, the centre tube of most stand varieties, and film or shop display lighting setups. The easy-grip handle and slotted design make it quick to attach and secure even in tight spaces.

Best for: Lightweight fixtures, shop displays, film lighting, small-format events where a standard 50mm clamp is physically too large.

Atom Hook Clamps
Doughty Atom Hook Clamp (25-38mm) Doughty Atom Hook Clamp (25-38mm)£7.70 View

Half Couplers (Wrap-Around Clamps)

Half Couplers (Wrap-Around Clamps)

A half coupler, also called a wrap-around clamp, provides a greater grip than a hook clamp because it fully wraps around the tube rather than just hooking over it. This makes it the preferred choice for heavier loads and situations where a hook clamp might twist or shift under the load direction.

The Doughty half coupler range fits tubes from 24mm to 63mm in diameter, covering the full spectrum from small studio bars to heavy-duty staging tube.

Best for: Heavier fixtures, situations where the load direction could cause a hook clamp to rotate, fixed venue installations where security takes priority over speed of rigging.

Doughty Half Coupler: 50mm Doughty Half Coupler: 50mm£22.64 View Doughty Half Coupler 50mm- Lightweight Doughty Half Coupler 50mm- Lightweight£19.89 View

The Doughty Twenty Clamp

One of Doughty's most distinctive products is the Twenty Clamp, named for its Safe Working Load. It is designed specifically not to damage lighting tubes or truss, which makes it the go-to choice for permanent venue installations where tube condition matters.

The Twenty Clamp has an SWL of 20kg, providing a reliable and gentle clamping solution for lightweight fixtures where preserving the tube surface is essential.

Best for: Permanent venue installations, situations where the tube or truss surface must not be marked or damaged, and venues with strict equipment protection policies.

The Doughty Twenty Clamp
Doughty Twenty Clamp - TÜV Approved Doughty Twenty Clamp - TÜV Approved£12.26 View

Gravlock Coupler

Gravlock Coupler

The Gravlock Coupler is a different type of clamp altogether. Unlike hook clamps and half couplers which are typically used individually, the Gravlock is designed to be used in pairs. Its self-locking mechanism makes it a favourite in touring environments where the same rig is assembled and de-assembled repeatedly. It fits the standard 48mm entertainment tube and is built for high-frequency, heavy-use applications where speed and security of connection are equally important.

Best for: Concert touring, repeated rigging and de-rigging, environments where speed and security of connection matter equally.

Doughty Gravlock Coupler per pair Doughty Gravlock Coupler per pair£51.50 View Doughty Gravlock Swivel Coupler per pair Doughty Gravlock Swivel Coupler per pair£51.50 View

Quick Comparison: Doughty Clamp Types at a Glance

Clamp Type Best For Max SWL / WLL Tube Diameter
Hook Clamp (50mm Medium-Duty) Standard stage and theatre use 100kg 48-51mm
Hook Clamp (50mm Heavy-Duty) Heavy luminaires 150kg 50mm
Atom Hook Clamp Film, shop display, small format 100kg (WLL) 25-38mm
Half Coupler Heavier loads, fixed installations 500-750kg 24-63mm
Trigger Clamp Heavy fixtures, one-person rigging 200kg 48mm
Quick Trigger Clamp Busy truss, fast rigging 250kg 48mm
Twenty Clamp Tube protection, permanent venues 20kg 48mm-51mm
Gravlock Coupler Touring, repeated assembly (used in pairs) 600kg per pair 48mm
  • How to Choose the Right Doughty Clamp

    Selecting the perfect Doughty clamp for your rigging setup depends entirely on your specific application, hardware dimensions, and safety requirements. To make the right choice, you must evaluate the total weight of your fixture, the exterior diameter of your truss or bar, and whether your installation is permanent or part of a fast-paced touring environment. Matching your exact scenario to the correct clamp ensures maximum safety, regulatory compliance, and efficiency during setup.

    You are rigging standard fixtures on a 48-51mm bar or truss

    The 50mm medium-duty hook clamp (SWL 100kg) is the most common choice. Affordable, straightforward to use, and rated for most conventional and LED fixtures.

    You are rigging a heavy moving head or follow spot

    Use the 50mm heavy-duty hook clamp (SWL 150kg) or a half coupler for extra grip security under a high or dynamic load.

    You are on tour and rigging the same rig repeatedly

    The Gravlock Coupler (used in pairs) is built for this. Its self-locking design is faster and more secure than a standard hook clamp in high-frequency rigging environments.

    You are working with small-diameter tubes (20-38mm)

    Choose the 20mm or 30mm hook clamp, or the Atom Clamp for tubes between 25mm and 38mm.

    You need to protect the tube surface

    The Twenty Clamp is specifically designed not to damage lighting tubes or truss.

    You need a fixture to hang from two bars or at a specific angle

    The double-ended range covers this, available in parallel and 180-degree twist configurations.

View Featured Products

Doughty Gravlock Coupler per pair
Doughty Gravlock Coupler per pair£51.50
Doughty Twenty Clamp - TÜV Approved
Doughty Twenty Clamp - TÜV Approved£12.26
Doughty Half Coupler 50mm- Lightweight
Doughty Half Coupler 50mm- Lightweight£19.89
Doughty Half Coupler: 50mm
Doughty Half Coupler: 50mm£22.64
Doughty Atom Hook Clamp (25-38mm)
Doughty Atom Hook Clamp (25-38mm)£7.70
Doughty 50mm Heavy Duty Hook Clamp (Steel)
Doughty 50mm Heavy Duty Hook Clamp (Steel)£8.88
Doughty 50mm Hook Clamp (Steel) - Medium Duty
Doughty 50mm Hook Clamp (Steel) - Medium Duty£5.39
Doughty 38-51mm Quick Trigger Clamp (TÜV approval)
Doughty 38-51mm Quick Trigger Clamp (TÜV approval)£26.94
Doughty 50mm Trigger Clamp
Doughty 50mm Trigger Clamp£21.55
View More

A Note on Safe Working Load

Every Doughty clamp is stamped with its Safe Working Load. This figure must never be exceeded. When calculating the load on a clamp, include the weight of the fixture, any accessories attached to it such as barn doors, gel frames, or gobos, and the weight of any cables running through the fixture.


Always fit a secondary retention device on every suspended fixture, regardless of which clamp you use. The clamp is the primary fixing. The Doughty safety bond is what catches the fixture if the primary fixing fails. Doughty safety bonds are available from 5kg to 100kg to cover every fixture type in your rig.

Frequently Asked Questions

A hook clamp attaches to a tube by hooking over it and is secured with a single bolt. A half coupler wraps fully around the tube for a greater grip. Hook clamps are faster to fit and suitable for most standard applications. Half couplers are preferred for heavier loads or where a hook clamp might twist under the load direction.
It depends on the clamp type. The most common standard for stage and entertainment rigging is 48mm to 51mm, which is what most hook clamps and the Gravlock Coupler are designed for. Doughty also makes clamps for 20mm, 25mm, 30mm, and 75mm tubes. Always check the product specification before ordering.
Each clamp is stamped with its individual SWL. The 20mm hook clamp is rated to 15kg SWL. The medium-duty 50mm hook clamp is rated to 100kg SWL. The heavy-duty version is rated to 150kg SWL. The Atom Clamp has a WLL of 100kg. Never exceed the stated rating.
The Gravlock Coupler is designed for touring and high-frequency rigging environments where the rig is assembled and de-assembled repeatedly. It is used in pairs and features a self-locking mechanism for faster, more secure connections than a standard hook clamp in repetitive use situations.
Yes. A safety bond is a secondary retention device that catches a fixture if the primary clamp fails. It is considered best practice in all professional entertainment environments and a requirement under UK health and safety guidance for suspended equipment. Doughty safety bonds are available in ratings from 5kg to 100kg.
Most Doughty hook clamps are designed for both bars and truss. The exception is the double-ended hook clamp for 75mm and 48mm bars, which is not recommended for truss use. Always check the product specification and confirm the tube diameter matches the clamp before ordering.

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