Take-up arm, load handling device and related storage and retrieval system

A take-up arm for a load handling device, the load handling device comprising:

• a body mounted on a first set of wheels being arranged to engage with a first set of parallel tracks and a second set of wheels being arranged to engage with a second set of parallel tracks;
• a direction-change assembly arranged to raise or lower the first set of wheels and or lower or raise the second set of wheels for engaging and disengaging the wheels with the parallel tracks;
• and
• a plurality of drive belt assemblies each comprising a drive belt, a drive wheel, and a take-up arm, wherein the drive belt is routed around a respective set of wheels, and the first set of wheels and the second set of wheels are driven by respective drive belt assemblies, the first set of wheels and the second set of wheels being driven wheels;
• the take-up arm comprising:
• a limb extending from one side of the direction-change assembly, the limb being horizontally displaceable relative to the drive wheel and the driven wheels when the direction-change assembly moves to raise or lower the set of wheels, and the drive belt is further routed around the limb, the drive belt having a drive belt route, wherein
• the limb is extendable, movable between a retracted position and an extended position, and wherein
• the limb is arranged to be in the retracted position when the wheels are lowered, and the limb is arranged to be in the extended position when the wheels are raised thereby extending the route of the drive belt and take-up slack in the drive belt when the wheels are in the raised position.