Post 135 - by Gautam Shah
Doors have THREE categories of HARDWARE:
1 BASIC HARDWARE attaches a shutter directly or through a frame to
an opening or doorway.
2 SECONDARY HARDWARE provides control on the movement of a
door.
3 APPENDAGES OR ATTACHMENTS that endow various types of
functionality.
BASIC HARDWARE for doors consists of shutter hanging
mechanisms. First doors had shutters of stone, wood, grass or reeds,
leaves, hides or skins, woven mats and fabrics. The shutters, in order to
open and close the opening, were made to swing, fold, collapse, slide
or roll up.
■ STRAPS: The primitive age door-shutter holders were straps of leather,
ropes, vines, and threads, and fabrics. Modern age doors have of
synthetic materials (plastics and composites) used as flexible hinges.
Straps are still used in some conditions where metal friction is likely to
cause sparks of erosion (petroleum solvent plants and cordite plants),
but are made from new technology materials such as woven Fibre glass,
Teflon, Cavalar, and carbon fibre composites.
■ PIVOTS: Early age large size doors and of heavier materials, such as stone, cast bronze and massive wood required pivots. Ancient doors were primarily hung by pivots, formed as a protrusion of the door material at the top and bottom as the hanging edge of the stile. The pivot rotated in sockets in the lintel and sill or thresholds in the floor. The pivots and the sockets, both of them were later encased with harder material such as granite, basalt, hard woods, bronze, iron, etc. Later day pivots were lined with metal sheaths. The other ends of the pivot, the nodes, were inserted into hard stone holes at floor and ceiling levels. Problems with pivot mechanisms were many: pivot nodes wore out fast -lowering and often tilting of the shutter, pivots broke frequently making shutter useless, and replacement of a worn or broken pivot requires a lot of structural changes. Pivots of cast bronze or iron were a better option, but required special joining with wood and more so with stone shutters.
■ PIVOTS: Early age large size doors and of heavier materials, such as stone, cast bronze and massive wood required pivots. Ancient doors were primarily hung by pivots, formed as a protrusion of the door material at the top and bottom as the hanging edge of the stile. The pivot rotated in sockets in the lintel and sill or thresholds in the floor. The pivots and the sockets, both of them were later encased with harder material such as granite, basalt, hard woods, bronze, iron, etc. Later day pivots were lined with metal sheaths. The other ends of the pivot, the nodes, were inserted into hard stone holes at floor and ceiling levels. Problems with pivot mechanisms were many: pivot nodes wore out fast -lowering and often tilting of the shutter, pivots broke frequently making shutter useless, and replacement of a worn or broken pivot requires a lot of structural changes. Pivots of cast bronze or iron were a better option, but required special joining with wood and more so with stone shutters.
Bank vault door with shelf Pivot hinges > Wikipedia image > WinonaSavingsBankVault.JPG by Jonathunder |
Pivots are fixed on the top and bottom corners, either exterior or interior face a door shutter, and also on the shutter side from a mid point to the corner of the shutter. Pivoted doors nominally open inside, but can as well swing in both directions. For pivoted doors no frame is necessary, however a projected edge of the portal frame can seal the edges and acts as a shutter stop. Pivots were difficult to insert, repair or replace, making way for development of hinges, and to a small extent sliding channels. Pivots fixed to side walls or frames are called pivot hinges or double-acting floor hinges, because opening movement is allowed in both directions as similar to hydraulic floor pivots (used for glass doors in modern buildings).
HINGES:
A hinge is component that ‘attaches one side edge of a door shutter to
the frame, while allowing the other edge to swing from it’. A hinge can also
be an arrangement, type of bearing that connects two solid objects
allowing a limited angle of rotation between them. Conceptually two
objects connected by a hinge ‘rotate relative to each other about a fixed
axis of rotation (the geometrical axis of the hinge)’. Hinges consist of a
pair of plates, each with a set of open cylindrical rings, the knuckles,
formed out of the plates, or attached to them. The knuckles of the two
plates are offset from each other and mesh together. A hinge pin is then
placed through the two sets of knuckles to form a single unit.
One door shutter usually requires minimum two, or more hinges.
Nominally three bands (horizontal members of a panelled door) have
three hinges, of which the top hinge is in ‘pull out stress’, the bottom
hinge is in ‘push in stress’ due to the cantilever action of the shutter
and the middle hinge is in ‘neutral stress’ state. All three hinges have
downward gravity bearing.
Butt or mortise Hinges are inset -mortised into the door stile and frame.
The hinge is fixed with its pin section (cylinder) remaining out of the door
face, to allow 180° of opening, i.e. the shutters can rest on the side of the
door opening. Sometimes mouldings over shutters, frames or casings,
however, interfere in the resting of the shutter, and for such conditions
hinges flanges of larger width are used or fixed with greater outward
projection of the pin section. Flanged Hinges formed of steel, bronze and
brass alloys are being used since middle ages. Hinges were viable with
smaller and lighter shutters. In case of pivots the bottom one carried the
load of the shutter, whereas the top pivot was mere holding element. But
in case of hinges, all of them shared the carriage of loads.
Early hinges began as a wall-hung or shelf-pivots, where the pivot-pin
was on a small shelf, hung off the sides, and the girth or ring was fixed
with the shutter. The wall-hung pivots were made of wrought iron or
bronze. These were much easier to insert after the masonry work, and
later, to repair or replace. Early shelf-pivots became long armed hinges,
and now have become an expression of the medieval door.
Modern hinges are available of brass, bronze, mild steel, stainless steel,
ABS and polypropylene plastics, carbon composites, etc. Most of the
commercial hinges are made of several components (such as flanges,
flange edge liners, pin, pin cylinder liners, coil springs, hydraulic cylinders,
etc.), and these are again composed of many different materials. Hinge
like movement systems are also employed in many types structures and
movable bridges. In biology many body joints function as hinges.
■ BUTT OR MORTISE HINGES: These are also known as shangles in
old Tudorian English. Butt or mortise hinges are made of hard wearing
and stiff materials. The pin is made of stainless steel, carbon steel, nylon
and Teflon, some of these materials do not require any lubrication.
■ FLUSH HINGES: These hinges are surface-mounted and do not
require a recess to be cut. These are not as strong as butt hinges, but can
be used for lightweight doors and small box constructions.
■ KNUCKLE HINGES: These are flush butt hinges, fixed over the face
of the door and its frame, and so not mortised. The pin cylinder or the
knuckle is designed to be visible.
■ PARLIAMENT OR BUTTERFLY HINGES: These were known as
Dovetail hinges and used for cabinets from the 17th C till 18th C. The size
and form of these hinges vary depending on the use, material and
manufacturer. Very small ones are used for jewellery boxes or caskets
and large ones used in public buildings (and so the name -parliament).
For deep-set door frames Parliament hinges park a deep-set shutter
along the corridor -at an opening angle of 180°.
■ STRAP HINGES: A strap hinge has a small height but a wider flange
that accommodates two or three screws in a row on each flange.
■ BACK FLAP HINGES: Back flap hinge is exactly the opposite version
of the strap hinge. It has a squarish flange (height and width are nearly
equal) Both are used in furniture items.
Living Hinge laser cut from Plywood > Wikipedia image by Autopilot |
■ LIVING HINGE: A living hinge is a thin strip moulded into a plastic part
to create a line along which the part can bend. If properly designed and
made, its ‘closing and opening capacity lasts for more than a million
cycles without failure’. It is a thin flexible hinge with flexure bearing. It is
formed during the injection moulding process for plastics or a composite
of it. Such hinges are used on lunch boxes and shampoo or hair oil
bottles, and are formed of deform-able plastics such as polyethylene, PVC,
polypropylene, etc.
PIANO Hinge |
■ PIANO OR CONTINUOUS HINGES: These hinges are long enough to
cover the entire length of the shutter, so support the shutter well against
warping. Very thin sections of shutter boards (non panelled, without
frames) require such hinges. These are used in cupboards, pianos,
baueras, and desk top shutters.
Nintendo Hinge > Wikipedia image by Evan-Amos |
■ INVISIBLE HINGES: These are used for joining two shutters. These
are fully mortised as centred on the door shutter’s face. Door shutters
seem like units of wall panelling as hinges are completely invisible.
■ CONCEALED HINGES: These are not seen outside a closed shutter,
such as for furniture doors. These are sometimes spring loaded with
self-closing features, and with or without a dampening system (slowing
down the closing speed during the last few degrees). They are made of
2 parts: One part is the hinge cup and the arm; the other part is the
mounting plate. The concealed hinges come in two sizes, 25 mm and 36
mm. The hinge once fitted is adjustable to correct the door alignment and
planner straightness. These hinges are designed for use with chipboard
and MDF.
Concealed Hinge > Wikipedia image by Julius Blum GmbH |
■ H HINGES: These are shaped like an H, and used on the flush
mounted doors. Small H hinges (75 to 100 mm) are used for cabinets and
larger hinges (150 to 175 mm) are used for passage doors or closet
doors. Large HL Hinges were common for passage doors, room doors
and closet doors in the 17th to 19th C. On taller doors H hinges were
occasionally used in the middle along with the HL hinges at top and
bottom.
Eastlake Style Door Hinge > Wikipedia image by Found5dollar |
■ BARREL HINGE: These Liftoff butt hinges have two components.
The bottom section has a cylinder or pin like projection over which a top
hollow ring or cylinder is set. The shutter can be lifted off its position for
servicing, cleaning etc. These are used in kitchen cabinets.
Lift off Hinges for Cabinets |
■ LOOSE PIN HINGES OR BALL TIPPED HINGES: These serve the
same purpose as the liftoff butt hinges. A removable pin holds two
halves of the hinge knuckles together.
■ STOPPED HINGE: This is like any butt hinge but a square cut
projection on the cylinder side of one flange restricts the opening of the
shutter to 90° only.
■ DOUBLE ACTION HINGE: These have three flanges. The middle
flange has hinged flanges on either side. The edge flanges are mortised
into the side of the shutter, but the middle flange remains off the sides.
The assembly leaves a space between the door shutter and its frame or
other shutter. The hinge allows the shutter to open in both directions.
Such hinges are used in saloon and bar doors.
Double action Hinge for Saloon and Bar doors |
■ DOUBLE ACTION SPRING HINGES: These are used on half height
saloon doors. The hinge allows the shutter to open in both directions, but
being a spring loaded mechanism, the closing action is automatic. In
another version of such a hinge, it is fixed to the frame, and the other
flange in the form of an arm has a roller at the edge. The shutter is often
provided with a plate or channel for the roller arm to slide.
■ UNEQUAL FLANGE HINGES: These have unequal flanges in terms
of width. A thin shutter has thin flange compared to wider flange for the
frame side. Unequal hinges also have a greater length of flanges to
compensate the reduced width of the flange.
■ FRICTION STAYS: Friction stays are fitted at top and bottom edges of
the surface, and used on French doors. Such hinges allow a door to
stay-put in its position in spite of the heavy winds, and so prove an ideal
fixture on windy faces such as sea shores, mountain valleys etc. The
hinge requires framing at least at the top and bottom, making it better
suited for windows. It has a sliding channel within which a component
fixed to the bottom of the shutter, for converting the rotational movement
of opening into a linear thrust, through a collapsible triangular
arrangement.
■ ASKEW OR VERTICALLY MISALIGNED PIVOTS OR HINGES: Fort
doors had askew or vertically misaligned pivots or hinges, so in case of
an emergency the door would be released from its catch to close fast, and
automatically. This mechanism required greater manpower to open it and
a stronger stay to keep it open. Similar systems are employed in modern
hospitals, class rooms, garden, and toilets doors, where closed doors are
preferred. Hydraulic or spring door-closer does the same function. In
refrigerators a magnetic gasket pulls and keeps the door shut. Some
refrigerators often have doors locking hinges on both sides, allowing a
door to be opened on left or right side. Salon and government offices
have flaps or mid door shutters, with a double flange hinge that can open
it both-ways, and also has a spring-coil to bring the shutter to the closed
position.
CLASSIFICATION OF HINGES:
CLASSIFICATION OF HINGES:
☐ Full Mortise Hinge has one leaf mortised into the door edge, and the
other leaf mortised into the door jamb. This is the most commonly used
hinge configuration. Hinge sizes are specified with height first and open
width second.
☐ Half Mortise Hinge configuration is used for door jambs that do not allow mortising, e.g. a channel steel frame. One hinge leaf is fixed to the door edge, and other leaf is surface fixed over the door frame.
☐ Half Mortise Hinge configuration is used for door jambs that do not allow mortising, e.g. a channel steel frame. One hinge leaf is fixed to the door edge, and other leaf is surface fixed over the door frame.
☐ Half Surface Hinge configuration, has one hinge leaf is fixed to the
surface of the door, and the other hinge leaf is mortised into the door
jamb.
☐ Structural Hinges include arrangements that link, two or more
components of a structure, but allow conditional movement without
letting them come apart or separate out in specific situations. The hinged
condition also allows transfer of loads, stresses and transmission of
energy. Such hinge like conditions occur in bridges, cranes, vehicles,
dams, canal and dyke structures.
☐ Gate Hinges are also called Building access hinges, and include
heavy duty hinges for fort gates, estate gates, hanger shutter hinges.
☐ Furniture or Cabinet Hinges include Concealed hinges with spring
loading, controlled closures; butter fly hinges, piano hinges, etc. A
butler tray and ambulance stretcher hinge (fold up the legs flat to 90E).
Card Table Hinges are mortised into the edge and allow the top (shutter
of card tables’ cavity) to fold onto itself. Drop Leaf Table Hinges are
mounted under the surface of a table with leaves that drop down.
Spectacle Hinge Flickr image by Guy Sie |
☐ Micro Hinges: Micro hinges are very small in size and used for
jewellery boxes, wall clocks, travel suitcases, attach, bag, micro
equipment and machinery cabinets. Many such hinges use ball-mortise
arrangement rather than cylinder-pin system.
☐ Floating Hinges: Behave as a normal hinge but enables one of the
objects to move away from the other, hence ‘float’. Actually the hinge
allows for two parallel axes of rotation, one for each object joined by the
hinge, and each axis can be moved relative to the position of the other.
Floating hinges are used in flatbed scanners designed to scan thick
objects such as books. A sheet of paper is placed on the glass, and the
cover is lowered over it. The scanner glass and the paper come together
very close. If a thick book is placed on the glass, an ordinary hinge would
leave the cover at an angle to the glass. A floating hinge raises the hinged
edge of the cover to the level of the book, so that the cover remains
parallel to the glass, but raised above it. Floating hinges are also used in
two-plate electric cooking grills, as they allow for even heating of both
sides of a thick piece of food without crushing it. Floating hinges are used
for air craft doors, Suzuki (Maruti) delivery vans, etc.
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