Air winches are used to pull or lift a load to a specific point. They have automatic holding brakes and are considered high-speed compared to the Griphoist or electric winches. When selecting an air winch for your next project, it’s not always simple as point and rent. Follow these guidelines to choose the correct utility winch for your next application:
First things first. Consider three fundamental questions:
- How much is to be lifted, pulled, or tensioned?
- How fast is the load to be moved (if at all)?
- How much wire rope is needed?
Lifting Applications are generally defined as those that require the brake to be engaged to prevent the load from falling. Here are a few considerations:
- Choose a winch with a lifting capacity equal to or greater than your application load.
- Make sure the average speed meets your criteria for cycle time.
- Wire rope selection is based on a 5:1 design factor and an 18:1 D/d ratio. The 18:1 D/d ratio is an ANSI / ASME B30-7 recommendation and is calculated as D + d/d where D = winch barrel diameter and d = wire rope size. The higher the ratio, the longer the wire rope life. As a guideline, this ratio should never go below 15:1. The use of 6 x 37 rope will increase flexibility.
- Either manual or automatic brakes are suitable, although automatic brakes are recommended for lifting applications.
- Clutches: In the U.S.A., clutches are permitted on lifting winches. Although we don’t usually recommend them, for certain lifting applications they make sense. In Europe, clutches are not allowed on lifting winches. The Liftstar series is for lifting and the Pullstar for pulling. They’re the same winches, but with different ratings – and the Pullstar winches have clutches, for that matter.
Winches can lift or pull the highest loads at the first layer, and can lift/pull the least at the top layer. This is due to the “torque arm” effect of the rope spooling on the winch drum. The closer the load is to the drum, the easier it is for the winch to turn and move the load. The further away the load is from the drum, the harder it is for the winch to turn.
Winches generally move the load fastest at the top layer and slowest at the first layer. Think of your old record player. If you put a penny near the center of the record, it would simply spin at the same rate as the record. But if you place it near the outside edge, it would fly off. This is because the outer diameter of the record is traveling faster than the inner diameter. The same is true for the winch drum, and consequently the wire rope.
Because of the 3:5:1 design criteria and the first layer rating, the ratings for pulling applications are higher for the same winch. Choose a winch based on capacity, speed, and distance to be pulled. Manual band brakes and clutches are popular configurations, but each application has its own specific requirements. Again, consider pulleys to increase pulling capacity.
All IR winches are rated at 90 psig (6.3 kg/m2) inlet pressure when the winch is running. The volume of air required is expressed in cubic feet per minute (cfm) or cubic meters per minute (m3/min.). Refer to the charts for air consumption data for specific models. Compressor output must equal air consumption for continuous operation. Intermittent operation and/or air storage facilities will allow the use of smaller compressors. Hoses and fittings should be sized equal to or preferably one size larger than the winch inlet. Strainers, lubricators, drum guards, filters, and regulators are recommended based on air quality and the application. Mufflers and kits for piping away the exhaust are always suggested for operator safety and comfort.
Contact your Lifting Gear Hire representative at 800.878.7305 or visit lgh-usa.com if you need additional assistance in guiding you through the selection process or if you have any questions.