A backshell is the accessory that terminates the cable at the rear of a circular connector. It provides strain relief, protects the contacts and, on shielded harnesses, grounds the braid. MIL-DTL-85049 is the qualified-products specification for these parts, and Glenair is the leading QPL manufacturer. Ordering the right one comes down to three questions.
1. Which connector family?
The slash sheet number identifies the connector the backshell fits and the style of the accessory.
| Slash sheet | Fits | Style |
|---|---|---|
| M85049/38 | MIL-DTL-38999 Series III | Straight strain relief |
| M85049/39 | MIL-DTL-38999 Series III | 90° strain relief |
| M85049/49 | MIL-DTL-5015, MIL-DTL-26482, MIL-DTL-83723 style | Strain relief |
| M85049/51 | MIL-DTL-26482 Series 2, MIL-DTL-83723 Series 3 | Straight strain relief |
| M85049/52 | MIL-DTL-26482 Series 2, MIL-DTL-83723 Series 3 | 90° strain relief |
| M85049/31 | MIL-DTL-38999 Series I and II | Cable clamp |
2. Which shell size?
The backshell shell size must equal the connector shell size. For a D38999/26WD35SN (shell size 15) you order an M85049/38 in size 15, for example M85049/38S15N. For MIL-DTL-5015 and 26482 connectors the /49, /51 and /52 sheets use the same 8 to 24 size numbers as the connector.
3. Which finish?
The last letter is the plating. N is electroless nickel, W is olive-drab cadmium over nickel, A is black anodize on some sheets. Match the connector: nickel connector, nickel backshell; cadmium connector, cadmium backshell. Mixed finishes set up galvanic corrosion at the coupling threads.
Self-locking or not?
On the /38 and /39 sheets an S after the slash number (M85049/38S13N) means self-locking, which uses a ratchet or spring feature so the backshell will not back off under vibration. Aircraft and vehicle harnesses almost always call for the self-locking version; bench and rack equipment often does not.
Protective covers
Do not confuse backshells with covers. D38999/32 (receptacle) and D38999/33 (plug) covers, and MS25042 / MS25043 caps for MIL-DTL-5015, protect unmated connectors in storage and transit. We stock both with and without lanyards.
Glenair stock in Los Angeles
Newcastle Industries carries more than 250 Glenair backshells, adapters and covers, including the full M85049/38 and /38S range in sizes 9 through 25. Browse the backshell inventory or send us the connector part number and we will match it.
Request a Quote or call (310) 845-1555. Newcastle Industries stocks these parts in Los Angeles and answers quotes within one business day.
