13.1 FOREWORD

Jacks are widely used in industry where loads need to be raised or lowered a limited distance. They are often used to afford access for other means of handling or lifting equipment and for levelling purposes. Their versatility of use and portability make them ideal for many maintenance functions. As a result, jacks have often been mistakenly considered as tools rather than lifting appliances.

Jacks are hydraulically or mechanically motivated by manual or power systems. The range of designs, sizes and capacities is almost limitless, and many manufacturers produce as standard jacks designed for a specific function, e.g. re-railing locomotives. This document focuses on common manually operated jacks, although excluded types may share similar requirements.

There are several modern standards throughout the world covering a wide range of mobile or movable jacks for various applications. The range includes hydraulically-operated, pneumatically- operated, electrically-operated and manually-operated jacks and jacks for road vehicles. However, prior to these there were very few standards for general purpose jacks and, as a result, many manufacturers produced, and continue to do so, a range of jacks to their own specifications.

Hydraulic cylinders (rams), with independent pumps connected by hoses, are often used in jacking applications. Although no specific guidance is given, the principles set out in this section of the code may be equally applied to certain cylinders when they are used for jacking purposes.