ProMark Offroad Blog
Drum Diameter and Line Speed for Offroad Winches
Along with the gear ratio, the drum diameter of your winch has a direct effect on line speed and pulling power. As more layers of cable pile up on the drum, the pulling power from your winch decreases and the line speed of the cable drops.
The rated line pull per layer drops up to 20 percent for the first layer of cable on top of the base layer and then 10 percent or more for layers after that.
Typical Rated Line Pull Per Layer
Example: 8000 lb. Winch
| Layer of Cable | 1st layer | 2nd layer | 3rd layer | 4th layer |
| Rated line pull per layer | 8000 lbs. | 6540 lbs. | 5550 lbs. | 4750 lbs. |
The smaller the diameter of the drum, the faster the layers pile up and the faster your pulling power drops. On the other hand, a larger diameter drum means that the size of the winch housing has to increase in order to make room for the cable wrapped around the drum. For vehicles with tight mounting spaces, this can be a problem.
Same thing goes for drum length. The shorter the winch drum, the faster the pulling power will drop. Yet the longer the winch drum, the bigger the winch housing needs to be.
The drum diameter and length of ProMark Offroad winches are designed to provide the best combination of optimal line speed and compact housing dimensions.
Planetary Gear, Worm Gear, and Spur Gear Winches
There are 3 basic types of winch gears: planetary, worm, and spur gears. The gear train’s job is to reduce the high speed power from the winch motor into a low speed, high torque pulling force. The main difference between these 3 types of winch gears is their transfer efficiency.
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Planetary Gear Winch
Transfer Efficiency: 65%
A planetary gear winch is the most popular and most affordable type of offroad winch. It offers strength, smooth operation, and good resistance to torque loads. They also allow for higher gear ratios than worm or spur gears. A planetary winch is typically the most compact of the three types of gear trains, making it the most practical type of winch for ATVs and vehicles with restricted mounting space.
Planetary gears got their name because of their design, similar to a sun with revolving planets. A braking system is required to hold the load.
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Worm Gear Winch
Transfer Efficiency: 35-40%
Worm gear winches are known for their endless endurance and high reliability. They are also self-braking, eliminating the need for a braking system. On the other hand, they are also mechanically less efficient than either planetary gear or a spur gear winch.
Compared to planetary winches, worm winches are heavier, more expensive, and more difficult to mount. Worm gear winches also have a slower line speed (especially in a no-load situation) and a higher amp draw than planetary winches.
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Spur Gear Winch
Transfer Efficiency: 75%
A spur gear winch is the most efficient type of winch, with a fast line speed and high reliability. Unfortunately, space requirements make it impractical to mount on some vehicles. If your vehicle has space restrictions for mounting a winch, the design of the spur gear winch may require extensive modifications to your vehicle.
Also, if you’re set on a spur gear winch, expect to pay a little extra. Very few spur gear winches are designed for offroad use. As with the planetary winch, a braking system is required to hold the load.
Planetary Gear Train
Worm Gear Train
Spur Gear Train
Photo Credits: “Planetary Gear Train” is licensed under the Creative Commons Attribution ShareAlike 3.0 License at http://commons.wikimedia.org/wiki/File:Train_planetaire.png.
Electric Winch Components
Electric Winch Components – Parts Diagram 1
Structural Components of an Electric Winch - Diagram 1
Solenoid (also known as Contactor) – The solenoid controls the direction that the drum will rotate. The solenoid receives power from your vehicle’s battery and protects the motor from overheating.
An integrated solenoid is permanently mounted over the winch (such as the Silverback winch package), and a remote solenoid is mounted separately from the winch (such as the XT winch package).
Steel Cable – The steel cable is wrapped around the winch drum and fed through the roller fairlead on the front of the winch. Synthetic rope is an alternative winch cable preferred by some offroaders for its ease of handling and safety.
Roller Fairlead – The fairlead guides the steel cable during the winching process and prevents the cable from getting snagged in moving winch parts. An aluminum fairlead is recommended for use with synthetic cable.
Electric Winch Components – Parts Diagram 2
Structural Components of an Electric Winch - Diagram 2
Internal Brake – The brake is the mechanism located inside the winch drum that keeps the load from slipping.
Gear Train (also known as Drive Train) – The gear train converts the power from the winch motor into a pulling force. The gear ratio is a major factor in the line speed.
Freespool Clutch – The freespool clutch allows you to engage or disengage the drum from the gear train. The freespool (disengaged) position allows you to freely spool out the cable by hand. The engaged position allows you to power out the cable.
