Abstract: A load measuring device for an aerial machine having a boom or jib which handles loads. A load bearing sheave has a winch line passed over it to raise and lower the load. A guide sheave maintains the winch line at a constant entry angle to the load bearing sheave. A dual axis load pin on which the load bearing sheave is mounted measures the force components of the load along two mutually perpendicular axes. Because the entry angle is constant, the load is dependent only on the two measurable force components and can be calculated and displayed. An overcenter machine has two load bearing sheave which are used alternately depending on whether the machine is overcenter or not. Each sheave in this case is mounted on a dual axis load pin.

Abstract: A mechanism for rotating an aerial platform carried on the upper end of a truck mounted aerial boom assembly. The upper boom tip carries a rotatable platform pin to which a rigid beam is secured to extend forwardly beyond the boom tip. The platform is a bucket mounted on the forward end of the beam for rotation about a vertical axis displaced well forwardly from the axis of the platform pin. A hydraulic cylinder rotates the bucket about its vertical rotational axis through a 90.degree. arc between a side hung position alongside the upper boom tip and an end hung position beyond the end of the boom tip. A spring loaded locking pin locks the bucket in the end hung position and provides a safety device that prevents the bucket from being rotated against a material handling jib that may be used in the side hung position of the bucket.

Abstract: A brake release arrangement by which damage which otherwise would result from the application of excessive side loading to rotating equipment such as the boom of a digger derrick or crane is avoided. The drive system for rotating the boom includes a hydraulic motor, a non self-locking speed reducer and a spring applied, hydraulically releasable brake. Included in the brake release mechanism is a line which taps into the hydraulic line leading to the power equipment mounted on the boom and whose operation develops side loads. An adjustable pressure reducing valve in the tap line provides a fluid output at a reselected pressure to a small chamber in the brake housing. The pressurized fluid in the chamber acts on a piston which, when the side loading on the boom is great enough to cause damage, partially relaxes the brake force thus to permit slippage and back drive of the speed reducer and motor thereby to relieve the side load torque.