S&G 8077

From Lockwiki
Revision as of 18:18, 12 February 2021 by Datagram (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigationJump to search

Sargent & Greenleaf 8077

Sargent & Greenleaf 8077
SG 8077 padlock.jpg
Name Sargent & Greenleaf 8077
Manufacturer Sargent & Greenleaf
Lock Type Padlock
Lock Design Combination
Year(s) Produced 19?? - Present
Related Locks
S&G 8065
S&G 8088

The 8077 is a UL 768-rated combination lock made by Sargent & Greenleaf. It is rated for 30 minutes of protection against manipulation and radiological attacks, and 10 minutes of protection against surreptitious attacks.

The 8077 is a newer version of the S&G 8088 and was the first padlock to meet Federal Specification FF-P-110J.[1]

Principles of operation

The 8077 is a combination lock that requires three numbers be correctly dialed into the lock for the shackle to be released. It uses three internal wheels and a fence-type mechanism similar to those used in traditional combination safe locks. The dial has fifty graduations numbered 0-49, giving the 8077 a total of 125,000 (503) theoretical permutations.

The 8077 functions very similar to traditional rotary combination safe locks. It uses a set of wheels, a drive cam, a fence, and a mechanism which resembles a butterfly. The butterfly hooks into the shackle, restricting its movement. When the correct combination is dialed the wheels and drive cam are properly aligned under the butterfly. Pulling the shackle causes the butterfly to collapse and pushes the fence into the gates, releasing the shackle.

The opening index mark is location at 12 o'clock on the face of the lock. The changing index, used to reset the combination, is located at 11 o'clock. All combinations are a three number sequence that ends with 0, for example 24-10-40-0 and 42-28-9-0. The last number is required to set the drive cam in the proper position. The factory combination is 25-0 (25-25-25-0), but older models may use 10-20-30-0.


  • The dial of the 8077 may be stamped with a two digit number to prevent casual replacement of the lock.

Opening instructions

These instructions use an example combination of 10-20-30-0

  1. Dial counter-clockwise four full revolutions, stopping on 10.
  2. Dial clockwise three full revolutions, stopping on 20.
  3. Dial counter-clockwise two full revolutions, stopping on 30.
  4. Dial clockwise to 0.
  5. Pull the shackle to unlock the padlock.

To dial the factory 25-0 combination (25-25-25-0), all wheels are dialed counter-clockwise four times, stopping at 25. Then dial clockwise, stopping at 0. Pull the shackle to unlock the padlock.

Combination change instructions

  1. Unlock the lock using the correct combination.
  2. Use the screwdriver end of the change key to turn the cover locking screw clockwise until it comes to a complete stop.
  3. Remove the padlock's rear cover plate by sliding it upward.
  4. Turn the padlock's cover locking screw counterclockwise, backing it out of the lock body as far as possible. It does not have a positive stop.
  5. Close the shackle.
  6. Dial the original combination, aligning each wheel with the changing index.
  7. Use the elbow of the change key to turn the key hole screw on the back of the lock clockwise to the open position.
  8. Insert the change key into the change key hole and turn in 90° clockwise.
  9. Dial the new combination, aligning each wheel with the changing index.
  10. Turn the change key 90° counter-clockwise and remove it from the lock. Do not close the change key hole!
  11. Dial the new combination to the opening index and open the lock. Open the lock repeatedly to ensure the new combination works before closing the change key hole.


  • The opening index is at 12 o'clock, the changing index at 11 o'clock.

Disassembly instructions

The 8077 cannot be disassembled non-destructively.



  1. Tobias, Marc (1971). Locks, Safes and Security: An International Police Reference. ISBN 0398070792.

See also