Abstract: This disclosure pertains to a toe unit for engaging a footwear toe of a footwear to releasably fasten the footwear toe to a snow travel aid. The toe unit comprises: a base for mounting on the snow travel aid; a slider slidably mounted on the base, the slider operably configured to resiliently slide laterally upon the base and away from a central position in response to a lateral force; opposable jaws mounted on the slider, wherein the jaws are moveable between an open and a closed position to releasably engage respective sides of the footwear toe in the closed position in order to fasten the footwear toe to the snow travel aid and to permit pivotal movement of the footwear about an axis intersecting the jaws. The opposable jaws are operable to move from the closed position to the open position independent of displacement of the slider from the central position in response to torque generated by rotation of the footwear about the footwear toe.

Abstract: A crank impact and wear protection article is disclosed. The crank arm includes a crank body and an impact and wear protection article coupled with the crank body.

Abstract: A method and apparatus is disclosed for controlling the flow of proppant into frac fluid during a frac. A first pressure source pressurizes fluid within a proppant addition unit. Process piping receives proppant through a proppant supply passage for supply to a frac pressure pump. A second pressure source pressurizes fluid within the process piping. A first sensor senses pressure on a first side of the proppant supply passage and outputs a first signal. A second sensor senses pressure on the process piping on a second side of the proppant supply passage and outputs a second signal. A processor receives the first signal and the second signal, and outputs a control signal to at least one of the first pressure source and the second pressure source in response to the first signal and the second signal to control proppant flow into the process piping.

Abstract: A method and apparatus is disclosed for controlling the flow of proppant into frac fluid during a frac. A first pressure source pressurizes fluid within a proppant addition unit. Process piping receives proppant through a proppant supply passage for supply to a frac pressure pump. A second pressure source pressurizes fluid within the process piping. A first sensor senses pressure on a first side of the proppant supply passage and outputs a first signal. A second sensor senses pressure on the process piping on a second side of the proppant supply passage and outputs a second signal. A processor receives the first signal and the second signal, and outputs a control signal to at least one of the first pressure source and the second pressure source in response to the first signal and the second signal to control proppant flow into the process piping.