# US 4,397,218 A · Cushion stop for hydraulic cylinder

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- Number: US 4,397,218 A
- Document ID: US4397218A
- Status: Granted
- Kind: A
- Application number: 06/219,997
- Filed: 1980-12-23
- Granted: 1983-08-09
- Earliest claimed: 1980-12-23
- Assignees: Allis-Chalmers Corporation
- Inventors: Donald K. Spring
- Web page: https://patentgrep.com/patent/US4397218A

## CPC

- F15B 15/225: {with valve stems operated by contact with the piston end face or with the cylinder wall}
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR

## Abstract

A cushioning device for decelerating and stopping the piston in a hydraulic cylinder by restricting and throttling the fluid flow from the cylinder.

## Claims

### Claim 1

A cushioning device in a hydraulic cylinder comprising, a hydraulic cylinder including a sleeve, a cap removably fastened on the end of said sleeve, a piston reciprocally mounted in said sleeve defining an expansible chamber with said cap, means defining a port in said cap, a check valve in said cap connected between said port and said expansible chamber providing inward flow from said port to said expansible chamber, means defining a plunger chamber connected between said port and said expansible chamber, a plunger received in an opening in said cap and extending into said plunger chamber axially aligned with the reciprocal movement of said piston, resilient means biasing said plunger toward said piston, means defining a central opening in said plunger forming an orifice on an inner end of said plunger communicating with said expansible chamber, radial openings axially spaced along said plunger connected to said central opening selectively closing and restricting fluid flow through said radial openings and limiting flow from said expansible chamber to said port as said plunger is pressed toward said cap as said piston reaches the end of the stroke to thereby provide a cushioning of said piston at the end of its stroke.

### Claim 2 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 wherein the outer end of said plunger defines a stop and abutment means engaging said stop in its extended position.

### Claim 3 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including a sleeve nut fastening said cap to said sleeve of said hydraulic cylinder.

### Claim 4 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including a removable cap screw means threadedly engaging a central opening in the end of said cap for removably retaining said plunger in said hydraulic cylinder.

### Claim 5 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 wherein said piston and said plunger define coaxially aligned axes.

### Claim 6 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including means defining a cylindrical opening receiving said check valve, a snap ring and spring in said cylindrical opening retaining said check valve in said cylindrical opening.

### Claim 7 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including, means defining a radial positioning of said port in said cap.

### Claim 8 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including means defining a peripheral shoulder on said plunger defining the limits of inner movement of said plunger in said cap.

### Claim 9 (depends on 1)

A cushioning device in a hydraulic cylinder as set in claim 1 wherin said resilient means defines a spring extending into the central opening of said plunger to bias said plunger toward said piston.

### Claim 10 (depends on 1)

A cushioning device in a hydraulic cylinder as set forth in claim 1 including, means defining at least two of said radial openings to restrict the flow from said expansible chamber to said port as said plunger is pressed into said cap.