Patent ID: 9568029
Date: 2017-02-14
CPC Classifications: B66F,F15B,F16H

Claim:
1. A hydraulic cylinder position sensing and locking system, comprising: a hydraulic actuator including: a hydraulic cylinder; and a plunger including a piston in the hydraulic cylinder and a threaded rod that extends axially from so as to move with the piston, the plunger being moveable axially relative to the cylinder in an extension direction and a retraction direction by selective supply of hydraulic fluid under pressure to the hydraulic cylinder; a lock nut that rotatably engages the threaded rod with a threaded connection therebetween; a drive unit that can be operated to rotate the lock nut relative to the plunger; a distance sensor that outputs a distance signal that is indicative of the axial spacing of the lock nut relative to the hydraulic cylinder; a rotary position sensor that provides a signal indicative of rotary position of the drive unit; and wherein the system determines the axial position of the plunger at least in part from the rotary position sensor signal, and a controller that receives as an input the distance signal and outputs a control signal to control the drive unit so as to turn the lock nut in correspondence with the axial movement of the plunger so as to maintain the spacing of the lock nut relative to the hydraulic cylinder within a desired range.