By Kent · Lock Depot Staff Writer

Three small locks that look alike and do not swap

Office furniture locks are the kind of job that gets ignored until a key goes missing. Then the person at the front desk wants it fixed today, the drawer is stuck shut with payroll in it, and the locksmith needs to know which lock is in there. Olympus makes three drawer locks that do this work and that get mixed up all the time: the N078, the R078 and the T37. All three are rekeyable. All three are small. They are not interchangeable, and the reason is in the barrel and the way they fasten.

The diamond back lock: N078 and R078

These two are the same style of lock. The catalog calls them a diamond back drawer lock, a cabinet lock for furniture drawers. Here is what they have in common, per the listings:

• Barrel diameter: 7/8 inch.
• Barrel length: 1-1/8 inches.
• Rekeying by a set screw cylinder release mechanism.
• Two keys per lock.
• The key removes in either the locked or the unlocked position.

Rekeyable on the spot saves a service call. The listing makes that point itself: rekeying is a time and money saver when a lock needs service. You do not need to pull the lock out of the drawer to change the key.

The difference between the two is the cylinder. The N078 listings are 4 pin and are listed with VH handing. The R078 listings are 5 pin and use the CCL R1 keyway. A 5 pin cylinder gives you more key combinations than a 4 pin, which counts for something when you have a lot of locks that must stay different from each other. If you are matching an existing lock, the pin count and keyway are what you match. Do not guess from the outside.

Keying options in the catalog:

• N078 in keyed different (N078-KD-26D), or keyed alike as KA 101, 103 or 915. Two examples are N078-KA101-US4 and N078-KA103-26D.
• R078 in keyed different (R078-KD-US4) or keyed alike as KA4T2 (R078-KA4T2-26D).

The finishes follow the usual short codes: US4 is satin brass and 26D is satin chrome. If the drawer pulls are brass, use US4. If they are brushed steel or chrome, use 26D.

The T-bolt lock: T37

The T37 is a different animal. It is a T-bolt metal drawer cabinet lock, and the catalog says it directly replaces the National C8137 T-bolt lock. It is made for metal drawers, specifically 1/4 inch thick ones, and the listing says an insertable T-bolt and a brass mounting nut are included.

• Barrel diameter: 3/4 inch. That is smaller than the diamond back locks.
• Pin tumbler, 4 pin cylinder.
• Uses the National D4291 keyway.
• Rekeyable through a working top slide and retainer staple cylinder release.
• Key removes in either position, two keys included.

The listing says the Olympus T37 is the first easily rekeyable pin tumbler T-bolt lock on the market. I cannot check that claim myself, so take it as the maker's line. What I can say is that if you have a gray steel file cabinet or desk with a T-bolt lock that says National on it, the T37 is the replacement the maker points to. Two ways to buy it in our catalog: T37-KD-26D (keyed different) and T37-KA101-26D (keyed alike, KA101).

How to tell which one you have

Take the old lock out and measure before you order anything. Three checks settle it:

1. Barrel diameter. 7/8 inch points to the diamond back N078 or R078. 3/4 inch points to the T37.
2. How it fastens. A T-bolt that turns and catches the drawer frame, with a brass nut holding the lock in the metal, is a T37 situation. The N078 and R078 are the 7/8 inch furniture drawer locks.
3. The keyway and pin count. Look at the key. A 4 pin lock on a rekeyable body could be an N078 or a T37. A 5 pin R1 keyway is the R078.

If you cannot tell, send us a photo of the front, the back and the key, and measure the barrel. That is faster than ordering the wrong one and returning it.

Keyed alike or keyed different

This is a business decision, not a hardware one. A desk with four drawers and one person in the chair should be keyed alike, so one key opens all four. A shared office with locks on separate employees' drawers should be keyed different, so one lost key does not open everybody's stuff. The catalog sells both for all three families. Decide before you order, because you cannot easily go back on a pile of locks that are all the same. For more on the tradeoff, we have a guide on Olympus 200DW keyed alike versus keyed different. For a building that runs on interchangeable cores, the Olympus 725 SFIC lock fits better. And for file cabinet cam locks, see DCR4 and DCN4.

Rekeying without a service call

All three families are built to be rekeyed without pulling the lock out of the furniture. That is the reason to buy them over a plain cam lock. When an employee leaves with a key, or a drawer key goes missing, you do not have to replace the lock. You change the cylinder pins to a new key. The N078 and R078 use a set screw to release the cylinder. The T37 uses a top slide and a retainer staple. The mechanics differ, so keep the instruction sheet that comes with the lock. Put it in a labeled envelope with the spare keys and tape it inside the office manager's cabinet. Three years from now, nobody will remember which lock went where.

Keep a record of the keying code too. If you buy a keyed alike set today, the code is how you order an exact match next year. Without it, you are matching by key, and that takes longer.

What to send us for a match

• A photo of the lock face, the back of the lock and the key.
• The barrel diameter in inches.
• The drawer thickness, and whether it is metal or wood.
• How many locks, and whether they should be keyed alike or keyed different.
• The finish of the pulls and handles on the furniture.

That list is short on purpose. With it, we can name the right part number the same day.

Common questions

What does the T37 replace?

The catalog says it directly replaces the National C8137 T-bolt lock.

Are these locks rekeyable?

Yes. The N078 and R078 rekey with a set screw cylinder release. The T37 rekeys through a top slide and retainer staple cylinder release.

What is the difference between the N078 and the R078?

The listings show the N078 as a 4 pin lock and the R078 as a 5 pin lock on the CCL R1 keyway. Both have a 7/8 inch barrel.

What do US4 and 26D mean?

US4 is satin brass and 26D is satin chrome.

Do they come with keys?

Yes. The listings say two keys per lock.

The rest of the line is on our Olympus page. Send us the old lock, or a photo of it with a measurement, and we will match it.