There are three main types of torque machines classified by their clamping mechanism:
1. Planetary Gear & Cam Clamping
A hydraulic motor drives a large gear via a reduction mechanism. Its internal teeth actuate planetary gears, which in turn rotate coaxial cams to clamp the pipe.
Advantages: Simple structure; no tool replacement required for different pipe diameters.
Disadvantages: Clamping force is applied at an angle rather than perpendicularly. Only 3 to 5 linear contact points may leave deep indentations. Thin-walled pipes are prone to deformation under high torque.
Application Limit: Pipe diameter ≤ 7 inches.
Models: YNJX160, YNJX210
2. Wedge Roller Clamping
The motor drives a gear fitted with 3 to 4 inclined plates. Rollers installed on sliding jaws travel along the inclined surfaces to close the jaws and grip the pipe. A brake band mounted on the housing provides controlled friction.
Advantages: Perpendicular clamping force; 6 to 12 contact points greatly reduce surface marks.
Disadvantages: Tool replacement is necessary for different pipe diameters; working range is restricted by structural design.
Key Note: So-called "mark-free tongs" on the market only minimize marks through curved jaw design. Low initial friction may lead to slippage.
Models: YNJG180/20, YNJG230/30, YNJG400/68, YNJG570/68
3. Synchronized Hydraulic Cylinder Clamping
Three to six hydraulic cylinders drive independent jaws that allow full continuous rotation.
Advantages: Wide clamping range with no tool change needed; adjustable clamping force and mild surface marking. Specially coated jaws enable virtually mark-free clamping for CRA pipes, titanium and stainless steel pipes.
Disadvantages: Complex structure and higher cost.
Models: YNJQ300, YNJQ400, YNJQ470, YNJQ590
4. Hybrid Systems
Planetary main tong + Hydraulic backup tong: Model YNJX400/68Q
Wedge roller main tong + Hydraulic backup tong: Model YNJQ400/68Q
