# US 4,489,471 A · Hydraulic pulling tool

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,489,471 A
- Document ID: US4489471A
- Status: Granted
- Kind: A
- Application number: 06/556,920
- Filed: 1983-12-01
- Granted: 1984-12-25
- Earliest claimed: 1983-12-01
- Assignees: Gregory Tool Systems, Inc.
- Inventors: Jack T. Gregory
- Web page: https://patentgrep.com/patent/US4489471A

## CPC

- B21J 15/105: {Portable riveters (pliers for riveting B21J15/386)}
- Y10T 29/53743: Liquid
- Y10T 29/5383: having fluid operator
- B21J: FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES (rolling of metal B21B; making particular products by forging or pressing B21K; cladding or plating B23K; finishing surfaces by hammering B23P9/04; compacting surfaces by blasting with particulate material B24C1/10; general features of presses, presses for consolidating scrap B30B; furnaces in general F27)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A hydraulic pulling tool comprising a piston slidable within a cylinder and having a co-axial bore therein. Lateral passages open from the bore through the piston to the leading face thereof and a screw piston is pushed in the bore by threading a screw pusher so that the hydraulic fluid in the bore is forced out into the cylinder to retract the piston. For a blind riveter, a pair of jaws is driven by a pusher piston also carried at the leading end of the bore so that the build up of pressure causes the jaws to grip a blind rivet firmly.

## Claims

### Claim 1

A hydraulic pulling tool comprising:
a cylinder;
a main piston slidable in said cylinder;
an axial bore extending into said main piston;
a plunger slidable in said bore;
at least one port opening from said bore to the leading face of said main piston;
an extension on the leading end of said main piston extending through the head of said cylinder;
work-piece gripping means on said extension;
mechanical means for forcing said plunger into said bore; and
means biasing said main piston toward said cylinder head.

### Claim 2 (depends on 1)

The hydraulic pulling tool defined by claim 1 wherein said plunger comprises:
a free transfer piston slidable in said bore;
internal threads in said bore at the trailing end thereof; and
a threaded pusher engaging behind said transfer piston.

### Claim 3 (depends on 1)

The hydraulic pulling tool defined by claim 1 wherein said gripping means comprises:
a collar with a conical inner surface carried on the leading end of said extension;
at last two jaws having complementary conical outer surfaces axially movable in said collar; and
a jaw pusher piston slidable in said bore so that fluid pressure behind said pusher piston forces said complementary conical surfaces together.

### Claim 4 (depends on 1)

The hydraulic pulling tool defined by claim 1 wherein said gripping means comprises:
a screw threaded into the body end of a said extension and adapted to engage a threaded blind fastener;
and including:
an anvil sleeve with a flat leading face carried on said cylinder; and
means forming an opening through said leading face through which said screw extends.