Strain relief fitting

• US 4,150,250 A
• Filed: 07/01/1977
• Issued: 04/17/1979
• Est. Priority Date: 07/01/1977
• Status: Expired due to Term

• Current Assignee: General Signal Corporation (SPX Corporation)
• Original Assignee: General Signal Corporation (SPX Corporation)
• Inventors: Lundeberg, Russell E.
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): Tone, D. A.
• Application Number:
  US05/812,196
• Time in Patent Office: 655 Days
• Field of Search: 174/65 SS, 174/65 R, 248/56, 339/107, 339/103 B, 339/103 R, 339/103 C, 403/342, 403/195, 403/197, 403/23.8, 285/114, 285/115, 285/116, 285/354, 285/340, 285/322
• US Class Current: 174/655
• CPC Class Codes: H02G 3/065 with means biting into the conductor-insulation, e.g. teeth-like elements or gripping fingers H02G3/0675, H02G3/0683 take precedence

Abstract

In many assemblies it is desirable to provide a strain relief device to grip an electric cord to prevent longitudinal motion of the cord, with respect to the strain relief device. The disclosed strain relief member surrounds the electric cord and is enclosed within a body member which, when assembled, applies longitudinal compressive forces on said strain relief member to cause a central portion thereof to collapse axially inward and grippingly engage the electric cord. The central portion may include serrations for improved restraining of the cord. The strain relief member may be made of plastic or metal and may include central perforations and/or portions of different thicknesses to facilitate and control the collapse. A metallic strain relief member may serve ground metal sheathed cable. A resilient membrane in a plane normal to the longitudinal axis of the cord and the strain relief member may be used between the strain relief member and the body member to provide a liquid tight seal. The collapsing feature of the strain relief member permits a strain relief member of predetermined proportions and characteristics to be used with a wide range of cable sizes.

Claims

1. A cord grip for restraining a cord against longitudinal motion with respect to said cord grip and comprising in combination:

(a) a cylindrical shell extending longitudinally about an axis and having first and second ends for loosely surrounding a cord to be restrained;

(b) said cylindrical shell including a plurality of spaced apart members connecting said first and second ends;

(c) each of said spaced apart members being similar and having an upper, a lower and a central section having a thinner wall thickness than other portions of said spaced apart members; and

wherein

(d) the interior diameter of said cylindrical shell has a minimum value in the plane of said central section whereby said spaced apart members will collapse radially inward in said plane in response to axial compressive forces on said ends.

2. The combination as set forth in claim 1, wherein the separation between said spaced apart members is reduced in response to the radial inward collapse of said spaced apart members.

3. The combination as set forth in claim 9, wherein the width of the separation between said spaced apart members limits the maximum extent of the radial inward collapse of said spaced apart members by the edges of said spaced apart members contacting each other as the width of said separation at, at least, one point is reduced to zero in response to the radial inward collapse of said spaced apart members.

4. The combination as set forth in claim 1, wherein the interior surface of said spaced apart members includes surface irregularities.

5. The combination as set forth in claim 4, wherein said surface irregularities are situated on said central portion of said spaced apart members.

6. The combination as set forth in claim 1 and including a sealing grommet for restricting the transfer of liquids from one side of said grommet to the other.

7. The combination as set forth in claim 6, wherein said sealing grommet comprises a disc portion with a central opening.

8. The combination as set forth in claim 7 and including a body member comprising first and second members threadingly engaged and enclosing said cylindrical shell and said grommet.

9. The combination as set forth in claim 8, wherein said first and second members include first and second surfaces, respectively, with said first surface contacting said first end, and with said grommet situated between said second end and said second surface.

10. The combination as set forth in claim 1 and including a body member comprising first and second members threadingly engaged and enclosing said cylindrical shell.

11. The combination as set forth in claim 10, wherein said first and second members include first and second surfaces, respectively, for contacting said first and second ends, respectively.

12. The combination as set forth in claim 11, wherein said first and second surfaces exert compressive axial forces on said first and second ends when said first and second surfaces are brought closer together in response to an increased threading engagement between said first and second members.

13. The combination as set forth in claim 1, wherein said cylindrical shell comprises a nonconducting material.