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Web Access: http://mtsc.usps.gov/pdf/mmo/2005/mmo08605.pdf
This Maintenance Management Order (MMO) provides information on new PSIN O910A
(clockwise rotation) and O910B (counter-clockwise rotation) locks used in centralized delivery
and collection equipment.
A new generation of centralized delivery and collection equipment is either now available to the
field or in process for near term release. Critical to the overall security success of both the new
and older generations of delivery equipment are the newly redesigned 0910A & O910B locks.
These new, security enhanced locks are INCLUDED with new Cluster Box Units (CBU),
Outdoor Parcel Lockers (OPL), and certain Indoor Parcel Lockers (IPL).
When ordering O910A and O910B spares from Topeka Material Distribution Center (TMDC),
only new type locks will be shipped. These locks have USPS-L1172C impressed on the front.
See Figure 4. They will mount in older generation CBU, Neighborhood Delivery Collection Box
Units (NDCBU), OPL and IPL equipment only by using a special adhesive washer shown in
Figure 6. The original (older generation) O910 lock will not fit in new equipment.
The attachment includes detailed information on the new O910A and O910B locks, pictures of
both original and new type locks, with differences clearly shown. In addition, instructions for
installation in most older generation equipment are included.
Direct any questions or comments concerning this bulletin to the HelpDesk, Maintenance
Technical Support Center, P.O. Box 1600, Norman OK 73070-1600; telephone FTS 2000 (405)
573-2123 or toll free (800) 366-4123.
Earl J. Jones
Manager
Maintenance Technical Support Center
Maintenance Policies and Programs
Attachment: PSIN 0910 Detailed Information and Installation Instructions
MAINTENANCE TECHNICAL SUPPORT CENTER / MAINTENANCE POLICIES & PROGRAMS
ENGINEERING / UNITED STATES POSTAL SERVICE
maintenance management order
SUBJECT: New Centralized Delivery PSIN O910A &
O910B Locks
December 22, 2005
MMO-086-05
DATE:
S2
FILE CODE:
TO:
All Maintenance Capable Offices
lser:mm05093af
NO:

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ATTACHMENT
PSIN 0910 DETAILED INFORMATION AND INSTALLATION INSTRUCTIONS
The original O910A and O910B locks were designed to fit in “Double D” type mounting holes.
See Figure 1 for drawings of the original Double D lock mount and new 1172C lock mount.
Original “DD” Lock Mount
New 1172C Lock Mount
Figure 1
Figure 2 shows the back side of the original lock. The arrows indicate the shape that fits in the
“DD” mounting hole.
Figure 2
Figure 3 shows the front of one supplier’s version of the original lock.
Figure 3

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Figure 4 shows the front of the NEW O910A and O910B lock (also known as 1172C).
Figure 4
Figure 5 shows the back side of the 1172C. Note the difference (indicated by arrow) between
this new lock and the original (Figure 2).
Figure 5
When mounting the 1172C in older generation equipment, a special adhesive washer (Figure 6)
must be used.
Figure 6

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Also spacer washer(s) as shown in Figure 7 may be required to achieve proper fit.
Figure 7
Part numbers for Lock Kits:
5340-02-000-8190 O910A (clockwise rotation)
5340-02-000-8005 O910B (counter-clockwise rotation)
Each kit includes the following:
• Locks (10)
• Spring clip (10)
• 5/16-24 nut (10)
• Adhesive-backed washer (10)
Part numbers for spare washers:
5310-08-000-3528 Adhesive Washers - 10 in package
5310-08-000-3529 Spacer Washers - 10 in package
The tools listed in Table 1 are recommended for installation and removal of locks:
Table 1
eBuy Item #
Item
Locate
Clean, dry paper or cloth towel
Locate
Screwdrivers (flat blade)
3ZE91
Ratchet, 3/8 in. Drive
3ZB28
19 in. Ext., 3/8DR, for NDCBU’s
3ZB66
½ in. Socket 3/8DR
1UG30
½ in. Nutdriver for NDCBU's
4YT04
Standard Pliers
4RU49
Tongue-and-Groove Pliers
4JA64
Vise Grips Pliers

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PSIN O910 LOCK INSTALLATION PROCEDURES
NOTE
Due to the variety of centralized delivery equipment, the steps
below are not all inclusive. Their primary purpose is to introduce
the importance of proper installation of the new type of lock with
the special adhesive washer. The use of the adhesive washer is
mandatory due to higher security requirements.
1. Using an Arrow Lock key, open the master door(s) of the unit for access to the lock to be
replaced.
2. Note the orientation of lock, cam, and spring clip. Remove the lock’s hardware and lock.
(For most lock removals, the NDCBU requires the use of the nutdriver or ratchet with drive
extender to reach the nut on the lock.) (If replacing a lock on a plastic American Locker
CBU, note the orientation of the spring clip before removing. This clip will be used for
securing the new lock).
3. Clean the mounting surface with a clean dry towel (for proper adhesive performance
surface must be absolutely clean) as shown in Figure 8.
NOTE
The adhesive washer is to be installed on the INSIDE of all
METAL boxes and on the OUTSIDE of all the PLASTIC boxes.
Figure 8 shows preparation for a plastic American Locker CBU.
Figure 8
CAUTION
Internal cylinder damage can occur if lock is installed with key
inserted.
4. Ensure key is not in lock. Peel off the liner from the washer exposing the adhesive as
shown in Figure 9.
Figure 9

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5. Properly align the lock, considering cam placement, and insert with adhesive washer in
place, through the Double D mounting hole as shown in Figure 10.
Figure 10
6. Ensure the spring clip is oriented the same as before removal and slide the clip into place
through the grooves closest to the backside of the door. Use pliers or vise grip to slide the
clip completely onto the lock (See Figures 11 and 12). If working with an American Locker
CBU, reuse the original clip.
Figure 11
Figure 12

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Spacer washers may be required for the spring clip to provide proper snug fit of lock.
Figures 13 and 14 show the spacer washer and example of their use.
Figure 13
Figure 14
7. Place the old cam on the lock and hand tighten the new nut. Do not attempt to use the old
nut due to difference in thread. See Figure 15.
Figure 15

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8. It is important that the cam be used as a stop (not the lock cylinder) while tightening the
nut. Excessive torque applied to the lock will damage and/or destroy the internal parts of
the cylinder mechanism. Use pliers or vise grips to “secure” the cam while tightening.
Figures 16 and 17 show examples of ensuring no torque is applied to the cylinder.
Figure 16
Figure 17
9. Tighten the nut until the cam is completely seated.
10. Insert the key and check for proper operation of the new lock before closing the door.
Close door and repeat operational check.

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