Models: All Models

Subject: Cold Weather Cautions

By: Glenn Smith, Engineering Manager

No. UL-011

Date: 3/3/92

What are the concerns when operating hoists and winches in cold weather conditions?

Caution: Sub-freezing temperature is a hostile environment to most equipment, including hoists and winches, and is outside the intended normal working environment.

Both functional and structural integrity of hoists and winches can be impaired when subjected to sub-freezing operating environments, and caution should be observed. Because of the wide-range of variables involved, it is difficult to predict how a piece of equipment will perform in any given situation. Generally, only the user of the equipment knows the application well enough to make decisions about extraordinary equipment needs. As manufacturers, we can suggest a few basic cautions that will go a long way toward avoiding problems when using equipment in sub-freezing environments.

FUNCTIONAL INTEGRITY

Caution 1- Keeping Equipment Dry

Controls, controls linkage, and brake linkages in particular are susceptible to malfunction due to formation of ice that can restrict their movement. This is true of all equipment whether it be manual, electric, air and/or hydraulic driven. Therefore, rule number one to follow when using hoists and winches in sub-freezing environments is to avoid ice accumulation by keeping equipment dry.

Situations where the hoist or winch is being cycled between warm and cold usually are the most troublesome applications. Typically warm-to-cold cycling occurs when moving in and out of a heated building, or the equipment is exposed to the warming of the sun by day, and then the freezing cold of night.

Steps to take to keep the equipment dry vary, depending on application. For instance, a rain cover may be employed.

Caution 2- Observe temperature limitations of lubricants.

Lubricants "stiffen" in cold temperatures, which can cause loss of equipment performance, malfunction and/or wear problems. Substituting lubricants specially formulated for cold temperature can extend the functional operating temperature range of equipment. Appropriate substitutions vary with product and application.

For pneumatic hoists and winches only:

Caution 3 - Dew point of compressed air supply to air powered equipment must be lower than ambient temperature. (When the compressed air is expanded to atmospheric pressure.)

 STRUCTURAL INTEGRITY

Caution 4 - De-rate load capacity of hoist by one-half when used in sub-zero temperatures (O° F, -18° C or lower)

Structural metals lose ductility and shock resistance in extreme cold temperature environments. It is good and common practice to de-rate load capacity of critical equipment used in sub-zero environments by one-half to regain a measure of shock resistance lost to cold temperatures. This practice assumes that there is not a user specification for the application that specifically addresses and quantifies shock resistance requirements.

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