Abstract: A manually operated mechanical rod holder has a support arm pivotally mounted on a drill rig chassis. A fixed jaw is mounted on an outboard end of the support arm. A movable jaw is mounted on a plate secured to a sleeve carried by the support arm. The sleeve is connected to an outer end of a sliding block that is slidably mounted in the sleeve. An inboard end of the block is connected to an outer end of an arcuate spring section integral with an operating lever. The inner end of the spring section is connected pivotally to an end of a link, the other end of which is pivotally mounted on the support arm. An inboard end of the operating lever has a handle. The throw of the movable jaw with respect to the fixed jaw remains constant. The distance between the movable jaw and the fixed jaw can be varied to accommodate different sizes of pipe or rod.

Abstract: In a hollow earth auger head assembly a plurality of bit-holding pockets are provided, spaced circumferentially from one another around an open mouth of an auger head, and bits taken selectively from a multiplicity of types of cutting teeth, have a shank portion that seats in any and all of the pockets. A retaining pin extends chordally, off set from a diameter, through holes in the pocket and into a retaining pin receiver in the bits. In those bits that are intended to rotate in the pocket, the retaining receiver takes the form of an annular channel. In those bits that are not supposed to rotate, the retaining pin extends through a linear passage in or along a flat on the bit shank. In certain embodiments of sockets a chordal plug or weldment defines a space with one flat side against which a tail of the shanks of certain bits designed not to rotate bear.