# US 5,344,120 A · Airless spray gun needle assembly

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- Number: US 5,344,120 A
- Document ID: US5344120A
- Status: Granted
- Kind: A
- Application number: 08/056,676
- Filed: 1993-05-03
- Granted: 1994-09-06
- Earliest claimed: 1993-05-03
- Assignees: Graco Inc.
- Inventors: Jimmy W. S. Tam; Lawrence L. Lanerd; Albert W. Lubenow; Tera D. McCutcheon
- Web page: https://patentgrep.com/patent/US5344120A

## CPC

- B05B 1/304: {the controlling element being a lift valve}
- Y10S 239/19: Nozzle materials
- B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A needle assembly for an airless spray gun is provided with a needle which is centerless ground and electropolished to greatly increase life. Further life enhancements are gained by use of a plastic needle bushing in the needle clamp and provision of a specific length to diameter geometry for the needle yields enhanced life as well.

## Claims

### Claim 1

A needle assembly for an airless spray gun, said needle assembly comprising:
a needle; having first and second ends and a sealing area, said needle having a centerless ground and electropolished surface, said needle being plated on one of said ends and unplated on the other of said ends;
a needle retainer retaining said needle first end; and
a ball retainer containing said needle second end.

### Claim 2 (depends on 1)

The needle assembly of claim 1 further comprising a soft needle bushing in said needle retainer, at said least part of said needle passing into said needle retainer.

### Claim 3 (depends on 2)

The needle assembly of claim 2 wherein said needle bushing is comprised of a relatively soft low density polyethylene.

### Claim 4 (depends on 1)

The needle assembly of claim 1 wherein said needle has a radius R in inches and a length L in inches between said needle retainer and said sealing area wherein L/(R.sup.2) is between about 70 and 140.