HYDRAULIC LOCKING DEVICE

• US 3,860,098 A
• Filed: 12/22/1971
• Issued: 01/14/1975
• Est. Priority Date: 08/01/1969
• Status: Expired due to Term

• Current Assignee: Clyde R. Porter, Percy L. Porter
• Original Assignee: Clyde R. Porter, Percy L. Porter
• Inventors: Porter, Percy L., Porter, Clyde R.
• Primary Examiner(s): Halvosa, George E. A.
• Application Number:
  US05/211,074
• Time in Patent Office: 1,119 Days
• Field of Search: 188/300,312,314,315 248/354H 297/355
• US Class Current: 188/300
• CPC Class Codes: B60N 2/929 linear
• CPC Class Codes: F15B 15/24 for restricting the stroke
• CPC Class Codes: F15B 15/26 Locking mechanisms

Abstract

A piston on a piston rod devides a cylinder into two hydraulic locking chambers, fluid flow between the two chambers being through the piston under control of a locking valve. A rotary adjustment sleeve of stepped configuration permits adjustment of the piston stroke. A reservoir for hydraulic fluid adjoins one locking chamber so that leakage from the chamber is into the reservoir. The reservoir is cut off when the piston moves out of its normal limit position.

Claims

1. In a locking device of the character described to control relative movement between two members, comprising a hydraulic cylinder connected to one of the two members, a tubular piston rod extending through at least one end of said cylinder and connected to the other of the two members, a piston united with the piston rod, the piston dividing the interior of the cylinder into two locking chambers, and a locking valve controlling fluid flow between the two chambers to control the freedom of movement of the piston, the improvement comprising:

a reservoir for hydraulic fluid to replenish the fluid in the two chambers, a portion of said tubular piston rod forming a wall of the reservoir, said reservoir having a movable wall;

means including a radial port in said portion of the tubular piston rod to permit flow of hydraulic fluid from the reservoir to one of said two locking chambers when the piston is at one of its two opposite limit positions, spring means acting against said movable wall of the reservoir to place the fluid in the reservoir under pressure for effecting flow to one of said locking chambers; and

sealing means embracing the tubular piston rod adjacent one end of the reservoir, said radial port being positioned along the length of the tubular piston rod to move out of communication with the reservoir into the region of said sealing means and past the sealing means when the piston moves out of one of its limit positions towards its other limit position whereby the reservoir is cut off from both of said locking chambers whenever the piston moves out of said limit position.

2. An improvement as set forth in claim 1 in which said sealing means separates one end of the reservoir from one end of said one of the two locking chambers whereby leakage from said one end of said locking chamber is into the reservoir.

3. An improvement as set forth in claim 1 in which said piston has a single normally closed valve located on its axis to control fluid flow between the two locking chambers and which includes an operating rod extending through the tubular piston rod to open said valve.

4. An improvement as set forth in claim 1 in which said piston rod extends through both ends of the hydraulic cylinder so that normally the total amount of fluid in the two locking chambers is constant throughout the range of movement of the piston.