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# Winches

## Effort force to raise a load.

A winch is a mechanical device that is used to wind up or wind out a rope or wire rope.

### Velocity Ratio

The velocity ratio can be calculated as

VR = R / r              (1)

where

VR = velocity ratio

R = effort force radius (m)

### Effort Force

The force to raise a load can be calculated as

F = W / μ VR

= W r / μ R

= m ag r / μ R              (2)

where

F = force (N)

μ = mechanical efficiency of the system (equal to one for an ideal friction-less system,  a fraction less than one for real-world systems with energy losses due to friction)

m = mass (kg)

ag = acceleration of gravity (9.81 m/s2)

W = weight (N)

### Example - Winch Effort Force

The effort force for a winch with small radius 5 mm and large radius 10 mm, efficiency 0.95 and load 1000 kg - can be calculated as

F = (1000 kg) (9.81 m/s2) (5 mm) / ((0.95) (10 mm))

= 5163 N

## Related Topics

• ### Dynamics

Motion of bodies and the action of forces in producing or changing their motion - velocity and acceleration, forces and torque.

## Related Documents

• ### Force

Newton's third law - force vs. mass and acceleration.
• ### Forces and Tensions in Ropes due to Angle

Reduced load capacities in ropes, cables or lines - due to acting angle.
• ### Polyester Polyolefin Ropes - Strengths

Polyester Polyolefin dual fiber 3-strand rope - minimum breaking strength and safe load.
• ### Polyester Ropes - Strengths

Polyester 3-strand and 8-strand rope - minimum breaking strength and safe load.
• ### Polypropylene Fiber Ropes - Strengths

Polypropylene fiber 3-strand and 8 strand rope - minimum breaking strength and safe load.
• ### Power

Power is the rate at which work is done or energy converted.
• ### Pulleys

Pulleys, blocks and tackles.

• ### Sisal Ropes - Strengths

Sisal rope 3-strand, minimum breaking strength and safe load.
• ### Wire Rope Slings

Sling angles and influence on capacity.
• ### Wire Ropes - Strengths

6 strand x 19 wire (6x19) - minimum breaking strength, safe loads and weight.

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## Citation

• The Engineering ToolBox (2011). Winches. [online] Available at: https://www.engineeringtoolbox.com/winches-d_1782.html [Accessed Day Month Year].

Modify the access date according your visit.

4.10.13

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