Abstract: The linear motion arresting device has a stationary member with an internal bore. A mating piston, formed of a plurality of piston parts, is slidable in said bore. One piston part is connected to a prime mover and the others are slidable toward and away from, and lengthwise of, said one piston part. Each of the piston parts has an elongated groove extending parallel to the bore and with the grooves providing directly between piston parts, a ball receiving channel in which a ball may travel and with the channel extending axially of, and at an angle to, the bore and with portions of the two opposite ends of the grooves extending more radially inwardly of the bore than the other two. A relatively nondeformable ball is mounted for travel in the ball receiving channel. A spring construction moves the piston parts in opposite, axial directions until the more radially inward portions of said grooves contact said ball.