Recent Developments in Continuous Hinges

June 1, 2017
Continuous hinges are moving from a “Problem Door” option to a mainline solution for high-frequency and abusive-traffic applications.

Sagging doors have always been an opportunity for the professional locksmith. Hinge and backing tab deterioration are especially vulnerable in hollow-metal doors and frames.  Heavy traffic, abuse, lack of maintenance, corrosion, and inadequate frame attachments, all lead to premature failure.

When MIT-trained engineer Austin Baer introduced the Roton continuous geared hinge, things changed – for the better.  The full-surface center pivot and swing-clear geared continuous hinges offered especially attractive and durable retrofit solutions.

Continuous hinges come in two basic varieties: pin and barrel (piano hinge style), and aluminum geared hinge versions (Roton style).  Industry insiders tell us that the stainless steel versions of the pin and barrel hinge have some advantages in hospitals, food service, or areas where harsh cleaners or corrosive chemical atmospheres might be an issue. Increasing regulation, market forces, and steel costs have sent most of the pin and barrel hinge manufacturing jobs offshore. 

On the other hand, the geared aluminum continuous hinge tends to have more load-bearing capacity, a wider range of applications and considerably lower cost than do the pin and barrel design.  Increased automation of the extrusion, machining, and anodizing processes have helped keep aluminum geared continuous hinge costs down.  Three-hour fire ratings are now available with both types, and both types distribute the load over the entire edge of the door and frame.

Full-surface hinges that fit tight door jams have now made retrofit applications pretty much universally practical. Narrow-faced frame versions now allow full-surface aluminum geared continuous hinges to be applied to most existing doors with no need for surgery on the door or frame.

Distributing the weight and kickback across the entire door and frame edge, dramatically increases the load the hinge can carry and life-cycle of the assembly. Hinge maintenance is becoming a thing of the past.  The most startling fact is that one continuous gear aluminum hinge has tested to 25-million cycles – 10-times the ANSI/BHMA A156.26-2012 American National Standard for Continuous Hinges.

The industry has seen considerable development and change since Baer filed his first patent in 1963 and introduced the geared continuous hinge. [i]   Since that time, there have been three primary developments: industry change and consolidation, design and manufacturing improvements, and electrical power and data transfer. 

Design & Manufacturing

After the original geared continuous hinge invention, Baer filed two additional patents that continue to influence the industry to this day.  His first patent in 1963 covered the basic geared continuous hinge design.[ii]  In 1968, the inventor added a patent for thrust bearings placed in recesses.  In 1990, the entrepreneur added a third patent with inserts above and below each bearing to reduce frictional contact.  

Additional industry developments to the geared continuous hinge include lifetime lubricated bearing materials, improved anodizing processes with multiple colors, and specialty applications like tight clearance models for narrow frame widths.  Fire ratings up to and including 3-hours are now generally available.  Anodizing after machining is completed has helped reduce bacterial harboring crevices and is a contributing factor to exceptionally long life spans in geared continuous hinges.  Some pin and barrel continuous hinges also now come with lifetime lubricated bearings between the knuckles. These pin and barrel hinges are available in mild steel and stainless.

Installation accuracy has been aided by three methods.  The R2 developed X-Y adjustment slots are being adopted by the Ives division of Allegion. In addition, Hager, Roton and others also provide adjustable mounting slots.  Select Hinges™ provides a complete detailed video to visually explain each step of the install process.

In another development, United States Bulletproofing Inc. (doors) and Select Hinges™ teamed up to gain Department of State Certification for Forced Entry (FE) and Ballistic Resistance.  Sledgehammers, pry-bars, wedges, long rifles (5.56 and 7.62 calibers), and other tools were employed in the tests.  [iii]  Additional frame pins are installed with this option.

Fire Ratings

Pin and Barrel hinges made from stainless steel have no trouble meeting the 3-hour rating since the material is typically stable up to 2,500 F.  Since aluminum melts at around 1221 F, it would not normally achieve a 3-hour rating.

Three basic methods are employed to meet the 3-hour standard in geared continuous hinges.  The first method is achieved by fixed pins mounted in the door, which engage pockets in the frame as the door closes.  The second method is accomplished with spring-loaded, thermally activated stainless steel pins.  These are held in place in the door by a fusible retainer.  When door temperature reaches approximately 350F, the fusible retainer melts, allowing the pin to project into a pocket in the frame.  

A third method, patented by Select Hinges®, is achieved with a hinge cover made from an intumescent material that swells under heat, providing a passive fire protection barrier. All three of these methods have passed UL certification for use on 3-hour rated assemblies. 

Power & Data Transfer

Increasing demand for electromechanical locking devices has driven the need to deliver power to the door.  Networked smart locks plus door and latch monitoring needs continue to be factors as well.  Virtually all continuous hinge manufacturers have responded with a copious variety of power and data transfer options.

Power over Internet (POE) is becoming a popular option, with snap-in quick connectors and through-hinge options.  A number of other power options have emerged in recent years. Most manufacturers are now offering snap-in connectors and wiring harnesses compatible with locking devices.  Concealed wire conductors are generally available. Swing-out access power transfer panels also now make post-installation repairs and connections easy.  Standard EPT power transfer cutouts are offered in many cases as well for geared or pin and barrel configurations.

One of the more interesting developments is the removable access panel.  Several manufacturers offer this option, making quick work out of wire repair or replacement.  The Select Hinges™ Accessible Through Wire (ATW) option, comes with multiple wires for fast repair when or if ever needed.

In some cases, you will be called in to retrofit an existing continuous hinge to accommodate an electrified exit device or lock.  An external door cord or replacing the hinge are no longer your only options.  Two additional retrofit innovations are worth noting.

With “need often the “mother of invention,” we sometimes see interesting developments outside the hinge industry, as well as the many inside.  Securitech®, the Maspeth, NY supplier of high-security locking devices developed a mini-hinge retrofit power transfer for geared continuous hinges. Retrofit mini-hinges are offered for a variety of existing brands. Concealed and full-surface models may be added to existing doors when electrified trim is used. The top 1-1/2” is removed and the mini-hinge installed in its place. An innovative wire technology has yielded more than 2,000,000 cycles.

Another intriguing development is the Inductive Current Power Transfer module introduced by Securitron®, the magnetic lock division of ASSA ABLOY in 2014.  This wireless power transfer device is gaining popularity in a number of applications. The ICPT is called PowerJump™.  The wireless power transfer module is rated at 6-watts continuous, and can be doubled-up to produce 12-watts.  In addition, a small capacitor can be charged and trigger an electrified device in milliseconds. The benefit for the Locksmith is that the ICPT device can be mounted in the hinge, or concealed anywhere in the door and frame.  This provides a way to get power to the door through concealed hinges, or independently for full surface applications. [iv] 

A couple of other power options are available. Hager Companies® offer concealed electric through-wire monitoring and power transfer with contacts on both door and frame that engage when the door is closed.  Concealed or exposed switches are also available, as are removable through-wire modules.

Industry Changes

The continuous hinge industry began to change in earnest after Baer’s original patent expired in 1985.  As early as 1976, Stanley® had shown interest in the Roton type hinge, but felt their manufacturing capabilities at that time did not fit well.  By 1988, it appeared that Roton held about 95% of the Continuous Geared hinge market. [v]  In 1989, Stanley® explored purchasing Roton, but did not come to terms. 

In 1990, Roton was acquired by the Hager Companies, who now produce both the Hager and Roton lines.  They remain one of the few independent manufacturers in the U.S. and have continued to thrive, despite the challenges of increasing regulation and international competition. The company operates from St. Louis corporate offices, with primary manufacturing in Montgomery, Ala.  They currently offer complete lines of continuous hinges with electrical components and fire ratings up to 3-hours, plus a complete line of commercial locks.

Inventor Baer came back into the market again about 2009. The entrepreneur started a company he called R2, introducing a product with post-installation adjustment slots for the X and Y axis. The R2 company did not gain much market traction at that time, and was subsequently acquired by Ives division of Allegion.

A Disruptive Technology Change

The geared continuous hinge appears to be one of those “disruptive technologies” that is changing how things are done.  As with most new technologies, adoption came slowly at first in specialty markets.  The innovation has become the preferred retrofit solution and is moving to broader use as the trouble-free longer life becomes apparent. 

Architectural Builder’s Hardware of Itasca, Illinois is now known as ABH, produces a complete line of geared, and pin and barrel continuous hinges, with all fire ratings. Electrical power transfer options are available, including EPTs, cut-out preps, concealed through-wires, and retrofit sections. ABH remains one of the strong independents in the continuous hinge business.

Bommer is one of the few independent survivors of the old hardware industry.  Theirs is a classic example of the transition through the “industrial age,” the growth of regulation, and finally, international competition.  The company was formed by Lorenz Bommer at the base of the Brooklyn Bridge in 1863.  They went on to become famous for their spring hinges. Increasing manufacturing costs led the company to less expensive overhead in Landrum, South Carolina in 1953.  The Soss hinge company was acquired in 1992, and consolidated into the South Carolina operation. The company remains focused on specific niches where they have particular strengths and expertise.

A major success story began shortly after Baer sold the original geared continuous hinge company.  In 1990, several of the former Roton reps joined forces and Select Products Ltd. was soon formed. The Portage, Michigan manufacturer was renamed Select Hinges®, and began a very successful run as a leading innovator in the continuous hinge marketplace. They have introduced a number of improvements that make electronic and retrofit applications easier for the locksmith. The company has remained independent, and is famous for their 25,000,000 cycle durability test.  Fire ratings and a full line of electronic power transfer options are available.

Swedish firm ASSA and Finish based Abloy companies merged in 1994, beginning an aggressive R&D and growth program.  They have emerged as a world-wide power in the door hardware industry.  The combined ASSA ABLOY organization has consolidated continuous hinge makers Markar and Pemko in Memphis, TN, and McKinney of Berlin, CT.  They have invested considerable research in efforts to integrate their electrified locks from Corbin/Russwin, Sargent, Securitron, Yale, and Adams Rite.  Part of the focus has been to reduce the power consumed by the electro-mechanical hardware on the door.

Ives became part of the Allegion group along with Von Duprin, Schlage, LCN, Falcon, Glynn-Johnson, Steelcraft, aptiQ electronics, and Zero hinges. Allegion’s continuous hinges have now been consolidated under the Ives brand. Allegion now carries a full line of pin and barrel and geared aluminum continuous hinges.  Fire ratings and electrical power transfer cutouts are available for most models. With the recent acquisition of the R2 brand, Ives now offers the X-Y adjustment slots for the geared continuous hinge line, along with “center weighted” bearing assemblies which allow the ends to be trimmed.

Stanley hinges, along with Best Access Systems and Precision (PHI) was just recently acquired by the Swiss company, dormakaba.  The Stanley Works was founded in 1843 by Fredrick T. Stanley in New Britain, Connecticut.  The company also grew through the “machine age,” and ultimately became an international player, acquiring and merging with a number of companies along the way.  In early 2017, StanleyBlack&Decker divested of the door hardware segments to focus on industrial and consumer tools.  Currently, Stanley hinges produce a complete line of continuous geared and pin and barrel hinges.  Fire ratings and a full line of electrical options are available.

National Guard Products (NGP) of Memphis, Tennessee is a recent entrant into the geared continuous hinge arena.  The company has introduced a broad line of the geared continuous aluminum products.  Metal parts are coated with a hydrophobic lubricant that prevents life-shortening dirt build-up. They currently offer fire ratings up to 90 minutes. 

PBB, located in Ontario, California offers complete lines of geared and pin and barrel hinges with fire ratings up to 3-hours.  Electrical preps, cutouts, and switch options are also available. 

Larsen & Shaw is a Canadian firm located in Walkerton, Ontario, west of Toronto.  They produce pin and barrel hinges in both stainless steel and aluminum.  Marlboro Manufacturing in Alliance, Ohio also produces pin and barrel hinges. 


It appears that continuous hinges are moving from a “Problem Door” option to a mainline solution for high-frequency and abusive-traffic applications.  The fact that all North American hinge manufacturers are aggressively moving into the aluminum geared hinge segment, gives us a clue to its significance.  Fire ratings, electrical connections and tight-jamb full surface applications allow the professional locksmith to apply this solution to nearly all applications. 

The significantly lower costs for aluminum geared hinges make them quite attractive, compared to the stainless steel pin and barrel models.  Watch some of the good installation videos that provide excellent perspective on how to be a problem-solver for your clients.[vi]

Author Cameron Sharpe, CPP worked in marketing for Caterpillar and Honeywell before serving 25-years with Best Lock Corporation in New Jersey and Arizona.