The following article is the first in a series discussing pivots, how they function and their interaction with surface mount, concealed and floor closers. This article will address pivot basics.
A pivot is a hinging device incorporating a fixed pin. Pivots are efficient movable joints for attaching a swinging door to a jamb. Unlike hinges, pivots are mounted along the top and bottom of the door. For doors of sufficient size, one or more intermediate pivots are also installed. The bottom pivot supports the entire weight of the door, while the top pivot keeps the door in alignment. Intermediate pivots are designed to help keep the door in alignment and prevent warping.
The basic pivot design is three main components: the leaf of the pivot mounted into the jamb or threshold, the leaf of the pivot mounted into the door, and the pivot stud that interconnects the two pivot portions.
There are two types of pivots – center-hung and offset. Center-hung pivots have their pivot point within door thickness center. An offset pivot has the pivot point located a distance from the heel edge and the face of the door. Center hung pivots are non-handed. They are double-acting, meaning the door can swing both ways if permitted. Offset pivots are always handed, and single acting. Offset pivots are usually easier to adjust than center-hung pivots. Many center-hung pivots require removal of the door to make adjustments.
Typically, offset pivots are available with the pivot point 3/4” from the heel edge of the door and 3/4” from the face of the door. This pivot is known as a 3/4” offset pivot. For thicker doors and specialized applications, the pivot point is 3/4” from the heel edge of the door and 1-1/2” from the face. This pivot is known as a 1-1/2” offset pivot.
Pivots come in three basic styles: top pivot, bottom pivot, and intermediate pivot. Unlike hinges, which are interchangeable, each pivot has a specific function and cannot be interchanged. Most top and bottom pivots are installed using screws that are mounted vertically into the door, jamb, and threshold. Screws in this position are less likely to become loose or pull out from the force exerted by gravity on the door.
Note: The top and intermediate pivots do not support the weight of the door. Only the bottom pivot is designed to support the weight of the door.
Pivots can be manufactured of a variety of metals. Pivots for 20-minute fire doors are non-ferrous. Most pivots are available in a number of finishes to match the finish of the door hardware.
Note: To ensure proper operation of the opening and closing of a door, make sure that all of the pivots attached to a door are from the same manufacturer.
Most hollow metal doors are constructed to accommodate either hinges or pivots, by having reinforcement built into the pivot or hinge areas. Most aluminum-glass storefront doors have reinforcement built in for pivots that can also accommodate an overhead concealed closer or a floor closer. For many replacement wood doors, the door rail and stiles have not been machined for either hinges or pivots. If you have any questions, contact the door manufacturer for their recommendations.
The sample door for this article was constructed by Rixson. The offset top pivot is the Rixson Model 180. The offset intermediate pivot is an M19, and the offset bottom pivot is a Model 147. The three Rixson pivots are bronze with hardened metal studs and other components for the pivoting surfaces.
The top and intermediate pivots are each equipped with an Oilite bearing. This oil impregnated bearing surface caps the metal pivot stud. The Oilite bearing is designed to provide a bearing surface for the stud to contact as the door swings keeping the door in proper alignment.
Rixson Model 147 bottom pivots are adjustable. The upper portion of this pivot is composed of a knuckle that is part of the pivot arm that is recessed into the bottom of the door. The arm is usually secured into the door bottom with four or more screws. Into the opening in the center of the arm knuckle mounts the pivot stud.
I was invited to the retrofitting of the lock hardware on a pair of wide stile aluminum doors equipped with rim exit devices latching onto a mullion.
Floor closer conversion & surface mounted door closer is installed.