One of the often forgotten hardware items on most commercial doors is the door closer. Door closers come in all shapes and sizes. By far the most popular type of door closer is surface-mounted. At one time a traditional surface-mounted closer consisted of a large vertical cylinder which housed a heavy, banded spring. Two smaller horizontal cylinders housed a piston which was immersed in oil. While this old style traditionally shaped door closer did control the door, esthetics and dependable long life were never strong points.
During the latter part of the 20th century traditional 'pot' shaped door closers were supplanted by a more modern shape of door closer. Band spring was replaced with a compression spring which is housed in the same horizontal chamber along with the piston. Streamlined door closer shapes of today have almost completely replaced the ugly door closer shapes of yesterday but dependability is still an issue.
When locksmiths are called to replace a defective door closer, DORMA is a name to remember. DORMA was originally founded in 1908 to make hinges. By 1950 DORMA was producing door closers. DORMA literature states "in revenue terms-we are today the world market leader."
Basic door closer construction usually consists of a rack and pinion. The pinion (shaft) is connected to a rack (piston) by gears. Door closer arms are directly attached to the shaft. Any rotational movement of the shaft will move the piston and affect the compression spring. The result is that as a door is opened, spring pressure is increased and as the door is closed, spring pressure decreases. Hinged door closer arms connect the shaft to the door jamb and provide a wide arc of rotational movement of the rack and pinion for controlled closing of the door.
DORMA 8600 rim mounted door closers have a full range of features. Their rack and pinion construction provides backcheck control plus dual adjustment valves control closing and latching. Spring size is field-adjustable from 1 to 6. The 8600 is non-handed. A flat arm design and a modern slim cover provide architectural grade aesthetic qualities.
A full range of door closer accessories are available for the 8600 door closer. These include regular arms, parallel arms, hold open arms and cushion arms. Drop plate, back plate and angle brackets are available for narrow top jamb or narrow stile installations. The DORMA 8600 provides the flexibility needed to meet the demands of commercial applications.
DORMA 8900 heavy duty rim mounted door closers have the same features as the 8600 but are designed for high traffic installations. Hardened rack and pinion parts plus forged arm parts provide toughness and long service life.
DORMA TS93 rim mounted track arm door closers contain a cam and roller design. A specially shaped cam is part of the door closer shaft. A round roller is part of the piston. As the shaft is rotated during door opening, piston movement is slowed or accelerated depending on the position of the cam. Careful cam design in the DORMA TS93 door closer provides optimum closing force as the door is latching.
DORMA TS93 track arm door closers provide a clean, modern appearance. Track arm installations also deter vandalism since there is no arm assembly projecting from the surface of the door. TS93 EMF models feature a photoelectric detector and electromagnetic hold/release device. T#93 GSR models are for coordinating a pair of doors and allow for sequencing of the doors. DORMA TS93 door closers are non-handed.
DORMA has a complete line of door closers and automatic door openers. For more information contact your local locksmith distributor or DORMA USA: 800-523-8483 or [email protected].
