# US 2012/0073133 A1 · Piston for a hydraulic motor having radial pistons, and a method of manufacturing such a piston

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- Number: US 2012/0073133 A1
- Document ID: US20120073133A1
- Status: Published application
- Kind: A1
- Application number: 13/314,469
- Filed: 2011-12-08
- Published: 2012-03-29
- Earliest claimed: 2006-03-31
- Assignees: Poclain Hydraulics Industries
- Inventors: Gilles LEMAIRE; Alain NOEL
- Web page: https://patentgrep.com/patent/US20120073133A1

## CPC

- F04B 1/0408: Pistons
- B23P 15/10: pistons
- F03C 1/0406: {Pistons}
- Y10T 29/49249: Piston making
- Y10T 29/49252: Multi-element piston making
- Y10T 29/49789: Obtaining plural product pieces from unitary workpiece
- Y10T 29/4979: Breaking through weakened portion
- Y10T 29/49792: Dividing through modified portion
- Y10T 29/49794: Dividing on common outline
- Y10T 29/49796: Coacting pieces
- Y10T 29/49798: Dividing sequentially from leading end, e.g., by cutting or breaking
- F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F)
- B23P: METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS (arrangements for copying or controlling B23Q)
- F03C: POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS (positive- displacement engines for liquids and elastic fluids F01; positive- displacement machines for liquids F04; fluid-pressure actuators F15B; fluid gearing F16H)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A piston for a hydraulic motor including a body having a guiding and sealing surface, a base, and a top, which top is providing with a cradle-shaped recess. The base is provided with an additional cradle-shaped recess whose concave surface faces in the direction in which the concave surface of the recess in the top faces.

## Claims

### Claim 1

A method of manufacturing pistons for a hydraulic motor having radial pistons, the method comprising the steps of:
providing longitudinal axis,
machining cylindrical transverse holes at regular intervals in the bar, and,
in order to form two adjacent pistons, cutting up the bar on a transverse cutting-up plane passing through a hole, so that a first portion of said hole forms a cradle-shaped recess in the base of the first one of the two adjacent pistons and so that another portion of said hole forms a cradle-shaped recess in a top of the second one of the two adjacent pistons.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the transverse cutting-up plane is offset relative to the transverse plane of symmetry of the hole through which said cutting-up plane passes so as to form two cradle-shaped recesses that are of different sizes, the smaller recess being the recess in the base of the first piston.

### Claim 3 (depends on 1)

A method according to claim 1, wherein additional machining operations, such as rectification, treatment, de-burring, coating, lining, turning and milling are performed on the bar before it is cut up.