AS 5227.1:2021 – Cranes-Requirements for mechanisms Part 1 : General (IsO 10972-1:1998,MOD).
4.3 Coupllngs
4.3.1 General
Selection or the type of coupling shall be made on the basis of the general design or the mechanism. its use and performance required in order to avoid vibrations and unwanted reactions. Alignment shall comply with the supplier’s instructions.
When necessary, rotating parts shall be statically or dynamically balanced.
4.3.2 Clutches
When sprag-type clutches are used in hoist and derricking systems, they shall incorporate a positive mechanical lock against failure or be designed to transmit twice the maximum torque imposed by the maximum line pull.
Dry friction clutches shall be protected against rain and other liquids such as oil and lubricants. Clutches shall be arranged to permit adjustments where necessary to compensate for wear.
The maximum permissible torque of the clutch shall be at least as high at any operating temperature as the torque impulses occurring during operations, taking into account the impulse frequency and the permissible wear.
4.4 Brakes
Means shall be provided br arresting each powered motion 01 the crane.
Emergency braking shall be performed using brakes which are automatically applied in case of power failure. The emergency brakes shall provide a deceleration rate consistent with the design parameters for a fully loaded mechanism.
The force to apply a manual in-service brake by hand or foot shall comply with the requirements of ISO 7752
The same brake maybe used for different types of braking, as appropriate.
4.4.1 Hoist brake
The frictional hoist brakes shall be capable or automatically arresting and sustaining any rated load and dynamic test load at any position within the range of hoisting
When emergency load-lowering is required, the hoist brake shall be capable of manual release so that control of the load will he maintained during lowering. The emergency load-lowering shall be carried out according to readily available Instructions which take Into account the hcat.dlsslpatlng capability of the brake,
The hoist brake shall be selected to have a nominal torque that Is at least 1.5 tImes the load torque.
Cranes intended for transportation of molten metals or similar hazardous materials shall be equipped so that dropping of the load Is prevented ha component In the force flow falls. This requirement Is met by
— having redundant systems, or
— an emergency stopping brake on the rope drum in conjunction with a redundant rope drive, or
— up to a gross load capacity of 16 t. designing the hoist at least two classification groups higher than required for actual operating conditions, and taking M5 as the minimum group.
4.4.2 Travel and slewing brake
Travel and slewing braking shall be capable of arresting the motion of a crane In the most unlavourable loading condition.
4.5 Out-of-service devices
When the mechanism Is not In use, Its position shall be retained by means of a brake or locking device. The locking device shall be arranged to avoid inadvertent engagement and disengagement. Engagement of the locking device shall prevent inadvertent operation of the motion.
When a crane is required to weather-vane in the out-of-service mode, the means of controlling this feature shall he operable from the control station. The device should operate automatically when
— the power supply to the crane is removed:
— the crane Is taken out of service.
4.6 Hydraulic and pneumatic systems
The general requirements presented in ISO 4413 and ISO 4414 for hydraulic and pneumatic systems shall be applied for cranes.
The hydraulic system and the control arrangement shall be such that no combination of control selections can Initiate any movement not intended by the operator, unless this Is essential for the operation of a safety device or interlock.
The circuits shall Incorporate the following safety features:
— relief valves shall he provided In pressurized hydraulic and pneumatic circuits In order to limit the maximum pressure in the circuit;
— safety devices to protect against the effects of failure of a hose, pipe or fittings In any load-carrying circuit on the crane.
All components and controls shall be capable of handling the design loads and shall provide safe function of the crane under regular, occasional and exceptional conditions, considering the failure of power source and the testing of the system.
All components and fluids (in a hydraulic system) shall be compatible with the application and the operational environment.
For diagnostic trouble-shooting, pressure test points shall be provided at the appropriate places in the system and be indicated on the circuit diagrams.