12.4.9 Jacks

Mobile supporting structure may be fitted with jacks which are intended to make the structure more permanent by taking the load off the castors. This is essential in the case of light duty castors. Some jacks are also designed to be used for levelling the structure and runway track. (See section 12.8.1 Installation of the Equipment and section 12.11 SAFE USE OF MOBILE SUPPORTING STRUCTURES) It should be noted that jacks intended for parking purposes, i.e. preventing movement by removing the weight off the wheels, may not be suitable for levelling purposes.