Abstract: A multi-section telescopic boom has sections with reinforced I-beam side walls and top and bottom walls made up of truss members. The trusses and beam stiffeners are disposed interiorly of the beam flanges so that the flanges provide continuous upper, lower and side bearing surfaces engageable with wear pads all of which are on the next outermost section. The lower and side wear pads are elastomer backed and the side pads have backup buttons that can easily be shimmed out to compensate for wear.

Abstract: A Ward-Leonard drive system for a dragline excavator includes a feedback circuit which connects to the motor-generator armature loop to sense a signal proportional to motor armature counter emf and rate of change of armature current. The feedback circuit takes the second derivative of this signal and applies it to a circuit which controls motor speed and torque. The feedback circuit alters the response of the drive system to sudden increases in motor load caused by rough digging and thereby reduces transient loading on the mechanical elements of the drive system.

Abstract: An outrigger system for use with mobile cranes, power shovels, and other vehicles requiring rigid ground support, comprises a telescoping beam outrigger system of the type having a pair of outrigger arms each of which comprises a beam telescopically stored in a horizontally disposed housing. The improvement comprises providing an arm construction in which the housing, as well as, the beam is extendible sidewardly. In a preferred embodiment the housing also tilts or translates downwardly as it is extended.

Abstract: A carousel-type drill rod rack handles a plurality of drill rods having normal diameter holding portions, flats below the holding portions, and reduced necks below the flats. The upper support plate has collars that receive the holding portions and have openings sized to allow removal only when the rods are raised to bring the necks in line with the plate. Cutouts in the upper support plate define two pairs of parallel straight surfaces that engage the flats to limit rotation in either direction but allow limited rotation to provide a breakout impact, and lugs that supportingly engage the shoulders above the flats. A travel lock means includes a rotatable ring with lobes movable into and out of alignment with the shoulders at the bottoms of the necks to prevent forward axial movement when the rack is horizontal and means to lock the ring in normal and lock positions.

Abstract: A torque feedback signal for the control system of a motor-generator set is generated by a torque feedback circuit which includes a differentiator and a current sensing circuit. The differentiator is connected to sense generator output voltage and provide an acceleration torque signal which is proportional to the first derivative of generator voltage. The current sensing circuit provides an induced torque signal proportional to motor armature current, and this is summed with the acceleration torque signal to provide a feedback signal proportional to the torque at the motor rotor. A second embodiment is shown which separates the induced torque into steady-state and transient components. The transient component is summed with the acceleration torque signal to provide a transient torque feedback signal, and the steady-state induced torque component is fed back to establish a torque limit.

Abstract: A shock absorber for dampening longitudinal and torsional vibrations in a drill is disposed intermediate a hollow drive shaft member and a hollow driven shaft member of a drill string. Resilient means are sandwiched between a drive plate attached to the drive shaft member and a driven plate secured to the driven shaft member. Additional resilient means are sandwiched between the driven plate and a pressure plate which surrounds the driven shaft member at a position beneath the driven plate. Pins project from the driven plate through the resilient means into vertically spaced openings formed in the drive plate and the pressure plate. Fastening means extend between the drive plate and the pressure plate to precompress the resilient means, and a shielding sleeve is connected to the drive shaft member for sliding movement within the driven shaft member.

Abstract: The guide bushing of a blast hole drill is resiliently mounted to dampen lateral vibrations of the drill string. The mounting arrangement comprises four pads symmetrically placed about the bushing and restrained against all but radial movement. Each pad includes a radially inner bearing section that bears against the exterior of the bushing, an outer backing section that is radially movable with respect to the bearing section, and a resilient cushion between the two sections. A four-lobed cam ring surrounds and faces the backing sections and is rotated to simultaneously load all the cushions to a selected degree. In the preferred embodiment, the mounting components are in an enclosed housing that defines guide channels for the pad and that can easily be fitted into the deck of a machine.