Although we usually think of older products as better made, this is not necessarily the case in all security hardware. While some mortise locks and unit locks are many decades old and still working fine, today's manufacturers are designing and introducing stronger and more vandal-resistant hardware.
In 1989 the Americans with Disabilities Act (ADA) was passed. The biggest impact on the locksmith industry was the proliferation of lever handle locks. On the positive side, the lever made it possible for persons with disabilities to gain entry to an unlocked door simply by pushing down on the lever. By its very definition, the lever added leverage that was missing in a knob lock.
A knob lock by design requires a gripping action to gain leverage. After gripping the knob, the wrist is turned to gain entry. Unfortunately, a disabled person with limited use of his or her hands could have difficulty gaining entry in a door most of walk through without a second thought. (Photo 1) Since a lever is designed to increase leverage, entry through the same door is made easier as a result of the ADA.
With the good news of easier access came the bad news of easier break-ins. Vandals and other unauthorized individuals quickly realized that levers were easier to defeat that most knobs. To defeat a knob, a small pipe wrench or similar tool was required to force the knob. The wrench gripped the knob and provided additional leverage to overcome it. This resulted in the need of carrying a large, bulky tool, which is very difficult to explain starting with "Officer, I was just …"
The lever had its own built-in leverage. By using a downward kick, the lock could be easily forced open. No wrench or other tool was required -- just stand on the lever.
Another disadvantage soon became apparent. By simply replacing the knob with a lever, the return springs soon wore out. The additional downward force resulted in drooping levers. Some major manufacturers experienced spring failures on locks that had been in the field for only a few months. If the droop was severe enough, the exterior lever had to be lifted up just to push in the inside locking button.
Levers come in various styles, but two distinct types: straight lever and return lever. The straight type lever may be curved in style but has no return at the open end of the lever. (Photo 2) The return type lever has a portion at the open end that returns toward the face of the door. An open ended straight lever can snag clothing, hoses, straps or loose items easily. The return is designed to keep clothing or fire fighter equipment from becoming caught on the lever. (Photo 3)
Some levers meet ADA code; some meet fire/life safety code; some meet both and some meet neither. The straight type lever meets ADA code if the lever is long enough to allow four fingers to grasp the lever without slipping off the end. The return type lever meets fire code if the return portion returns to within one-half inch of the face of the door. Most Grade 1 and Grade 2 commercial levers with a return will meet both codes. Some small Grade 3 residential levers have a return but may be too short to meet ADA requirements. (Photo 4)
NOTE: If there is any question in your mind, always check with the local Authority Having Jurisdiction (AHJ) to be sure the hardware you suggest or install meets all applicable codes and laws regarding ADA and Fire, Life Safety.
Lever manufacturers eventually solved the spring problem by designing larger escutcheons with spring cages inside. The addition of two through bolts also strengthened the lock mechanism. Depending on the manufacturer, the two through bolts might be positioned at 12 and 6 o'clock, at 10 and 4 o'clock or at 1 and 7 o'clock. Some of the new leversets have the ability to place the through bolts in different positions to accommodate an existing installation. Replacing a knob lock usually did not require drilling additional holes in the door. Sometimes replacing one lever with another requires re-drilling two or more holes.