Block and tackle sheave to change the direction of the pulling line, which increases friction losses without improving the velocity ratio. Situations in which reeving to disadvantage may be more desirable include lifting from a fixed point overhead; the additional pulley allows pulling downwards instead of upwards so that the weight of the lifter can offset the weight of the load. The formula used to find the effort required to raise a given weight using a block and fall: where formula_3 is the force applied to the hauling part of the line (the input force), formula_4 is the weight of the load (the
Lifting Operations and Lifting Equipment Regulations 1998 indicate safe working loads; ensuring that any equipment is positioned and installed so as to minimise risks; that the equipment is used safely ensuring that work is planned, organised and performed by a competent person; that equipment is subject to ongoing thorough examination and where appropriate, inspection by competent people. The regulations define lifting equipment as "work equipment for lifting or lowering loads and includes its attachments used for anchoring, fixing or supporting it". The regulations involve anything which involves the lifting of goods or people at work. Equipment covered would include lifts, cranes, ropes, slings, hooks, shackles, eyebolts, rope