Hinge

In this episode of the, I Can't Sleep Podcast, fall asleep learning about hinges. They may seem innocent, but don't let them fool you; hinges are everywhere! I guess that doesn't have anything to do with boredom. Nevertheless, ubiquitous hinges do the job. Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast,

Where I read random articles from across the web to bore you to sleep with my soothing voice.

I'm your host,

Benjamin Boster.

Today's episode is from a Wikipedia article titled,

Hinge.

A hinge is a mechanical bearing that connects two solid objects,

Typically allowing only a limited angle of rotation between them.

Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation,

All other translations or rotations being prevented,

And thus a hinge has one degree of freedom.

Hinges may be made of flexible material or of moving components.

In biology,

Many joints function as hinges,

Like the elbow joint.

History Ancient remains of stone,

Marble,

Wood,

And bronze hinges have been found.

Some date back to at least ancient Egypt.

In ancient Rome,

Hinges were called cardo and gave name to the goddess Cardea and the main street Cardo.

This name Cardo lives in figuratively today as the chief thing on which something turns or depends,

In words such as cardinal.

According to the OED,

The English word hinge is related to hang.

Door hinges Barrel hinge A barrel hinge consists of a sectional barrel,

The knuckle,

Secured by a pivot.

A barrel is simply a hollow cylinder.

The vast majority of hinges operate on the barrel principle.

Butt hinge Mortise hinge Any hinge which is designed to be set into a door frame and or door is considered to be a butt hinge or a mortise hinge.

A hinge can also be made as a half mortise,

In which case only one half of the hinge is mortised and the other is not.

Most mortise hinges are also barrel hinges by virtue of how they pivot,

I.

E.

A pair of leaves secured to each other by knuckles through which runs a pin.

Butterfly Parliament UK hinge These are a decorative variety of barrel hinge,

With leaves somewhat resembling the wings of a butterfly.

Case hinges Case hinges are similar to a butt hinge,

However usually more of a decorative nature,

Most commonly used in suitcases,

Briefcases,

And the like.

Concealed hinge These are used for furniture doors,

With or without a self-closing feature,

And with or without damping systems.

They are made of two parts.

One part is the hinge cup and the arm,

The other part is the mounting plate,

Also called cup hinge or euro hinge as they were developed in Europe,

And use metric installation standards.

Most such concealed hinges offer the advantage of full in situ adjustability for standoff distance from the cabinet face,

As well as pitch and roll by means of two screws on each hinge.

Continuous piano hinge This variety of barrel hinge runs the entire length of a door,

Panel,

Box,

Etc.

Continuous hinges are manufactured with or without holes.

Flag hinge These consist of a single leaf attached in the male variety to a pin.

When used,

The pin is inserted into the other female portion of the hinge.

This allows the objects to be easily removed,

For example a removable door.

They are manufactured in right hand and left hand configurations.

H hinge These barrel hinges are shaped like an H and used on flushed mounted doors.

Small H hinges,

3 to 4 inches,

Tend to be used for cabinet hinges,

While larger hinges,

6 to 7 inches,

Are for passage doors or closet doors.

HL hinge These were common for passage doors,

Room doors,

And closet doors in the 17th,

18th,

And even 19th centuries.

On taller doors,

H hinges were occasionally used in the middle along with the HL hinges.

Pivot hinge This hinge pivots in openings in the floor and the top of the door frame,

Also referred to as a double acting floor hinge.

This type is found in ancient dry stone buildings and rarely in old wooden buildings.

These are also called har-hung doors.

They are a low cost alternative to using the lightweight doors.

Self-closing hinge This is a spring loaded hinge with a speed control function.

The same as spring hinge,

Usually use spring to provide force to close the door and provide a mechanical or hydraulic damper to control door close speed.

That can prevent door slamming problems while auto closes the door.

Spring hinge This is a spring loaded hinge made to provide assistance in the closing or the opening of the hinge leaves.

A spring is a component of a hinge that applies force to secure a hinge closed or keep a hinge opened.

Swing clear hinge Swing clear hinges aka offset door hinges are perfect for residential and commercial doors as they allow doors to swing completely clear of openings.

Swing clear hinges can easily comply with Fair Housing Act FHA code by providing a minimum 80A 32 inch clearance when using a 34 inch door slab.

Closing hinge This hinge takes advantage of the flexibility of plastic to create a join between two objects without any knuckles or pins.

They are molded as a single piece,

Never become rusted,

Do not squeak,

And have several other advantages over other hinges,

But the plastic makes them more susceptible to breakage.

Other types include coach hinge,

Counter flap hinge,

Cranked hinge or storm proof hinge,

Double action non-spring,

Double action spring hinge,

Flush hinge,

Friction hinge,

Lift off hinge,

Hinge,

A hinge with a quick release pin,

Rising butt hinge,

Security hinge,

T key hinge.

Building access Since at least medieval times there have been hinges to draw bridges for defensive purposes for fortified buildings.

Hinges are used in contemporary architecture where building settlement can be expected over the life of the building.

For example,

The Dakin building in Brisbane,

California was designed with its entrance ramp on a large hinge to allow settlement of the building built on piles over bay mud.

This device was effective until October 2006 when it was replaced due to damage and excessive ramp slope.

Large structures Hinges appear in large structures such as elevated freeway and railroad viaducts.

Hinges are included to reduce or eliminate the transfer of bending stresses between structural components,

Typically in an effort to reduce sensitivity to earthquakes.

The primary reason for using a hinge rather than a simpler device such as a slide is to prevent the separation of adjacent components.

When no bending stresses are transmitted across the hinge,

It is called a zero-moment hinge.

Spacecraft People have developed a variety of self-actuating,

Self-locking hinge designs for spacecraft deployable structures such as solar array panels,

Synthetic aperture radar antennas,

Booms,

Radiators,

Etc.

Hinge Terminology Components Pin The rod that holds the leaves together inside the knuckle,

Also known as a pintle.

Knuckle The hollow,

Typically circular portion creating the joint of the hinge through which the pin is set.

The knuckles of either leaf typically alternate and interlock with the pin,

Passing through all of them,

Aka loop,

Joint,

Node,

Or curl.

Leaf The portions,

Typically two,

That extend laterally from the knuckle and typically revolve around the pin.

Characteristics End Play Axial movement between the leaves along the axis of the pin.

This motion allows the leaves to rotate without binding and is determined by the typical distance between knuckles,

Knuckle gap,

When both edges of the leaves are aligned.

Gauge Thickness of the leaves Hinge width Length from the outer edge of one leaf to the outer edge of the other leaf,

Perpendicularly across the pin,

Aka open width.

Hinge Length The length of the leaves parallel to the pin.

Knuckle Length The typical length of an individual knuckle parallel to the pin.

Leaf Width Length from the center of the pin to the outer edge of the leaf.

Pitch Distance from the end of a knuckle to the same edge of its adjacent knuckle on the same leaf.

Door Stop A colloquialism referring to loose angular movement of the leaves relative to the pin.

Other Types Butler Tray Hinge Folds to 90 degrees and also snaps flat.

They are for tables that have a tray top for serving.

Carpenter Joint A hinge consisting of several thin metal strips of curved cross section.

Card Table Hinge Mortised into edge of antique or reproduction card tables and allow the top to fold onto itself.

Drop Leaf Table Hinge Mounted under the surface of a table with leaves that drop down.

They are most commonly used with rule joints.

Hinged Handcuffs A restraint device designed to secure an individual's wrists in proximity to each other consisting of two cuffs linked with a double or triple hinge.

Hinged handcuffs tend to restrict movement more than chain-linked handcuffs and they can be used to generate more leverage to force a suspect's hands behind the back or to apply pain against the wrist forcing the subject to comply and stop resisting.

Piano Hinge Or Coffin Hinge,

A long hinge originally used for piano lids but now used in many other applications where a long hinge is needed.

Living Hinge A hinge consisting of material that flexes.

Mortise and Tenon A mortise and tenon occasionally mortise and tenon joint A mortise and tenon joint connects two pieces of wood or other material.

Woodworkers around the world have used it for thousands of years to join pieces of wood,

Mainly when the adjoining pieces connect at right angles.

Mortise and tenon joints are strong and stable joints that can be used in many projects.

They furnish a strong outcome and connect by either gluing or locking into place.

The mortise and tenon joint also gives an attractive look.

One drawback to this joint is the difficulty in making it because of the precise measuring and tight cutting required.

In its most basic form,

A mortise and tenon joint is both simple and strong.

There are many variations of this type of joint,

And the basic mortise and tenon has two components.

One the mortise hole and two the tenon tongue.

The tenon formed on the end of a member generally referred to as a rail fits into a square or rectangular hole cut into the other corresponding member.

The tenon is cut to fit the mortise hole exactly.

It has shoulders that seat when the joint fully enters the mortise hole.

The joint may be glued,

Pinned,

Or wedged to lock it into place.

The joint is also used with other materials.

For example,

It is traditionally used by both stone masons and blacksmiths.

Edemology The noun mortise,

A hole or groove in which something is fitted to form a joint,

Comes from circa 1400 from Old French mortais,

Possibly from Arabic mortas,

Fastened,

Past participle of razza,

Cut a mortise in.

The word tenon,

A noun in English since the late 14th century,

Developed its sense of a projection inserted to make a joint from the Old French tenir to hold.

History and Ancient Examples The mortise and tenon joint is an ancient joint dating back 7,

000 years.

The first examples,

Tusked joints,

Were found in a well near Leipzig,

The world's oldest intact wooden architecture.

These were created by early Neolithic linear pottery culture,

Where it was used in the construction of the wooden lining of the wells.

Mortise and tenon joints have also been found joining the wooden planks of the Khufu ship,

A 43.

6 meter long vessel sealed into a pit in the Giza pyramid complex of the 4th dynasty around 2500 BC.

Mortise and tenon joints have also been found in ancient furniture from archaeological sites in the Middle East,

Europe,

And Asia.

Many instances are found,

For example,

In ruins of houses in the Silk Road Kingdom of Kadoda,

Dating from the 1st to the 4th century BC.

In traditional Chinese architecture,

Wood components such as beams,

Brackets,

Roof frames,

And struts were made to interlock with perfect fit,

Without using fasteners or glues,

Enabling the wood to expand and contract according to humidity.

Archaeological evidence from Chinese sites shows that by the end of the Neolithic,

Mortise and tenon joinery was employed in Chinese construction.

The 30 Sarzan stones of Stonehenge were dressed and fashioned with mortise and tenon joints before they were erected between 2600 and 2400 BC.

A variation of the mortise and tenon technique called Phoenician joints was extensively used in ancient shipbuilding to assemble hull planks and other watercraft components together.

It is a locked,

Pegged mortise and tenon technique that consists of cutting two mortises into the edges of two planks.

A separate rectangular tenon is then inserted in the two mortises.

The assembly is then locked in place by driving a dowel through one or more holes drilled through mortise sidewall and tenon.

Description Generally,

The size of the mortise and tenon is related to the thickness of the timbers.

It is good practice to proportion the tenon as one third the thickness of the rail,

Or as close to this as is practical.

The haunch,

The cut-away part of a sash corner joint that prevents the tenon coming loose,

Is one third the length of the tenon and one sixth of the width of the tenon in its depth.

The remaining two thirds of the rail,

The tenon shoulders,

Help to counteract lateral forces that might tweak the tenon from the mortise,

Contributing to its strength.

These also serve to hide imperfections in the opening of the mortise.

Types Mortises A mortise is a hole cut into a timber to receive a tenon.

There are several kinds of mortise.

Open mortise,

A mortise that has only three sides.

Stub mortise,

A shallow mortise,

The depth of which depends on the size of the timber.

Also a mortise that does not go through the workpiece,

As opposed to a through mortise.

Through mortise,

A mortise that passes entirely through a piece.

Wedged half dovetail,

A mortise in which the back is wider or taller than the front or opening.

The space for the wedge initially leaves room to insert the tenon.

The wedge after the tenon is engaged prevents its withdrawal.

Through wedged half dovetail,

A wedged half dovetail mortise that passes entirely through the piece.

Tenons A tenon is a projection on the end of a timber for insertion into a mortise.

Usually the tenon is taller than it is wide.

There are several kinds of tenon.

Stub tenon,

A short tenon,

The depth of which depends on the size of the timber.

Also a tenon that is shorter than the width of the mortise piece so the tenon does not show,

As opposed to a through tenon.

Through tenon,

A tenon that passes entirely through the piece of wood it is inserted into,

Being clearly visible on the rear side.

Loose tenon,

A tenon that is a separate part of the joint as opposed to a fixed tenon that is an integral part of one of the pieces to be joined.

Biscuit tenon,

A thin oval piece of wood shaped like a biscuit.

Towed or pinned tenon.

The joint is strengthened by driving a peg or dowel pin,

Tree nail,

Through one or more holes drilled through mortise sidewall and tenon.

This is common in timber framing joints.

Tusk tenon,

A kind of mortise and tenon joint that uses a wedge shaped key to hold the joint together.

Diesel tenon,

A term used for the tenon on top of a jowled or gun stock post,

Which is typically received by the mortise and the underside of a tie beam.

A common element of the English tying point.

Top tenon,

A tenon that occurs on top of a post.

Hammer headed tenon,

A method of forming a joint tenon when the shoulders cannot be tightened with a clamp.

Half shoulder tenon,

An asymmetric tenon with a shoulder on one side only.

A common use is in framed,

Ledged and braced doors.

Bearing mechanical.

A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts.

The design of the bearing may,

For example,

Provide for free linear movement of the moving part or for free rotation around a fixed axis.

Or it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.

Most bearings facilitate the desired motion by minimizing friction.

Bearings are classified broadly according to the type of operation,

The motions allowed,

Or to the directions of the loads forces applied to the parts.

Rotary bearings hold rotating components such as shafts or axles within mechanical systems and transfer axial and radial loads from the source of the load to the structure supporting it.

The simplest form of bearing,

The plane bearing,

Consists of a shaft rotating in a hole.

Lubrication is used to reduce friction.

In the ball bearing and roller bearing,

To reduce sliding friction,

Rolling elements such as rollers or balls with a circular cross section are located between the races or journals of the bearing assembly.

A wide variety of bearing designs exist to allow the demands of the application to be correctly met for maximum efficiency,

Reliability,

Durability,

And performance.

The term bearing is derived from the verb to bear,

A bearing being a machine element that allows one part to bear,

I.

E.

To support another.

The simplest bearings are bearing surfaces,

Cut or formed into a part,

With varying degrees of control over the form,

Size,

Roughness,

And location of the surface.

Other bearings are separate devices,

Installed into a machine or machine part.

The most sophisticated bearings for the most demanding applications are very precise components.

Their manufacture requires some of the highest standards of current technology.

History The invention of the rolling bearing in the form of wooden rollers supporting or bearing an object being moved is of great antiquity.

It may predate the invention of a wheel rotating on a plane bearing.

Though it is often claimed that the Egyptians used roller bearings in the form of tree trunks under sleds,

This is modern speculation.

The Egyptians' own drawings in the tomb of Jehutiotep show the process of moving massive stone blocks on sledges as unique liquid-lubricated runners,

Which would constitute plane bearings.

There are also Egyptian drawings of plane bearings used with hand drills.

Wheeled vehicles using plane bearings emerged between about 5000 BC and 3000 BC.

The earliest recovered example of a rolling element bearing is a wooden ball bearing supporting a rotating table from the remains of the Roman Nemi ships in Lake Nemi,

Italy.

The wrecks were dated to 40 BC.

Leonardo da Vinci incorporated drawings of ball bearings in his design for a helicopter around the year 1500.

This is the first recorded use of bearings in an aerospace design.

However,

Agostino Ramelli is the first to have published sketches of roller and thrust bearings.

An issue with ball and roller bearings is that the balls or rollers rub against each other,

Causing additional friction.

This can be reduced by enclosing each individual ball or roller within a cage.

The captured or caged ball bearing was originally described by Galileo in the 17th century.

The first practical caged roller bearing was invented in the mid-1740s by horologist John Harrison for his H3 marine timekeeper.

In this timepiece,

The caged bearing was only used for a very limited oscillating motion,

But later on Harrison applied a similar bearing design with a true rotational movement and a contemporaneous regulator clock.

Industrial Era The first patent on ball bearings was awarded to Philip Vaughan,

A British inventor and iron master in Carbersen in 1794.

His was the first modern ball bearing design,

With the ball running along a groove in the axle assembly.

Bearings played a pivotal role in the nascent industrial revolution,

Allowing the new industrial machinery to operate efficiently.

For example,

They were used to holding wheel and axle assemblies to greatly reduce friction compared to prior non-bearing designs.

The first plain and rolling element bearings were wood,

Closely followed by bronze.

Over their history,

Bearings have been made of many materials,

Including ceramic,

Sapphire,

Glass,

Steel,

Bronze,

And other metals.

More recently,

Plastic bearings made of nylon,

Polyoxymethylene,

Polyetrafluorethylene,

And UHMWPE,

Among other materials,

Are also in use today.

Watchmakers produce jeweled watches,

Using sapphire plain bearings to reduce friction,

Thus following more precise timekeeping.

Even basic materials can have impressive durability.

Wooden bearings,

For example,

Can still be seen today in old clocks or in water mills where the water provides cooling and lubrication.

The first patent for a radial-style ball bearing was awarded to Jules Sourieri,

A Parisian bicycle mechanic,

On 3 August 1869.

The bearings were then lifted to the winning bicycle ridden by James Moore in the world's first bicycle road race,

Paris-Rouen,

In November 1869.

In 1883,

Frederick Fisher,

Founder of FAG,

Developed an approach for milling and grinding balls of equal size and exact roundness by means of a suitable production machine,

Which set the stage for creation of an independent bearing industry.

His hometown,

Schweinfurt,

Later became a world-leading center for ball bearing production.

The modern self-aligning design of ball bearing is attributed to Sven Wingfist of the SKF ball bearing manufacturer in 1907,

When he was awarded Swedish patent number 25406 on its design.

Henry Timken,

A 19th century visionary and innovator in carriage manufacturing,

Patented the tapered roller bearing in 1898.

The following year he formed a company to produce his innovation.

Over a century the company grew to make bearings of all types,

Including specialty steel bearings and an array of related products and services.

Eric Fronk invented and patented the wire race bearing in 1934.

His focus was on a bearing designed with a cross-section as small as possible and which could be integrated into the enclosing design.

After World War II he founded together with Gerhard Heydrich,

The company Fronk & Heydrich KG,

Today Fronk GmbH,

To push the development and production of wire race bearings.

Richard Strebeck's extensive research on ball bearing steels identified the metallurgy of the commonly used 100CR6,

Showing coefficient of friction as a function of pressure.

Designed in 1968 and later patented in 1972,

Bishop Weiss Carver's co-founder Bud Weiss Carver created V-groove bearing guide wheels,

A type of linear motion bearing consisting of both an external and internal 90 degree V angle.

In the early 1980s Pacific bearings founder Robert Schroeder invented the first bi-material plane bearing that was interchangeable with linear ball bearings.

This bearing had a metal shell,

Aluminum,

Steel or stainless steel,

And a layer of Teflon based material connected by a thin adhesive layer.

These ball and roller bearings are used in many applications,

Which include a rotating component.

Examples include ultra-high speed bearings in dental drills,

Aerospace bearings in the Mars rover,

Gearbox and wheel bearings on automobiles,

Flexure bearings in optical alignment systems,

And air bearings used in coordinate measuring machines.

One by far the most common bearing is the plane bearing,

A bearing which uses surfaces in rubbing contact,

Often with a lubricant such as oil or graphite.

A plane bearing may or may not be a discrete device.

It may be nothing more than the bearing surface of a hole with a shaft passing through it,

Or of a planar surface that bears another,

In these cases not a discrete device.

Or it may be a layer of bearing metal,

Either fused to the substrate semi-discrete,

Or in the form of a separable sleeve discrete.

With suitable lubrication,

Plane bearings often give entirely acceptable accuracy,

Life,

And friction at minimal cost.

Therefore,

They are very widely used.

However,

There are many applications where a more suitable bearing can improve efficiency,

Accuracy,

Service intervals,

Reliability,

Speed of operation,

Size,

Weight,

And costs of purchasing and operating machinery.

Thus,

There are many types of bearings with varying shape,

Material,

Lubrication,

Principle of operation,

And so on.

Types There are at least six common types of bearing,

Each of which operates on a different principle.

Plane bearing Consisting of a shaft rotating in a hole,

There are several specific styles.

Bushing,

Journal bearing,

Sleeve bearing,

Rifle bearing,

Composite bearing.

Rolling element bearings whose performance does not depend on avoiding or reducing friction between two surfaces,

But employ a different principle to achieve low external friction,

The rolling motion of an intermediate element in between the surfaces which bears the axial or radial load.

Classified as either Ball bearing,

In which the rolling elements are spherical balls.

Roller bearing,

In which the rolling elements are cylindrical rollers,

Linearly tapered,

Conical rollers,

Or rollers with a curved taper,

So-called spherical rollers.

Jewel bearing,

A plane bearing in which one of the bearing surfaces is made of an ultra-hard glassy jewel material,

Such as sapphire to reduce friction and wear.

Fluid bearing,

A non-contact bearing in which the load is supported by a gas or liquid,

I.

E.

Air bearing.

Magnetic bearing,

In which the load is supported by a magnetic field.

Flexure bearing,

In which the motion is supported by a load element which bends.

Motions Common motions permitted by bearings are radial rotation,

E.

G.

Shaft rotation,

Linear motion,

E.

G.

Drawer,

Spherical rotation,

E.

G.

Ball and socket joint,

Hinge motion,

E.

G.

Door,

Elbow,

Knee.

Friction Reducing friction in bearings is often important for efficiency,

To reduce wear and to facilitate extended use at high speeds,

And to avoid overheating and premature failure of the bearing.

Essentially,

A bearing can reduce friction by virtue of its shape,

By its material,

Or by introducing and containing a fluid between surfaces,

Or by separating the surfaces with an electromagnetic field.

By shape,

Gains advantage usually by using spheres or rollers,

Or by forming flexure bearings.

By material,

Exploits the nature of the bearing material used.

An example would be using plastics that have low surface friction.

By fluid,

Exploits the low viscosity of a layer of fluid,

Such as a lubricant or as a pressurized medium to keep the two solid parts from touching,

Or by reducing the normal force between them.

By fields,

Exploits electromagnetic fields,

Such as magnetic fields to keep solid parts from touching.

Air pressure exploits air pressure to keep solid parts from touching.

Combinations of these can even be employed within the same bearing.

An example of this is where the cage is made of plastic,

And it separates the rollers,

Balls,

Which reduce friction by their shape and finish.

Loads Bearing design varies depending on the size and directions of the forces that they are required to support.

Beams can be predominantly radial,

Axial,

Thrust bearings,

Or bending moments perpendicular to the main axis.

Speeds Different bearing types have different operating speed limits.

Speed is typically specified as maximum relative surface speeds,

Often specified feet per second or meters per second.

Radial bearings typically describe performance in terms of the product dN,

Where d is the mean diameter,

Often in millimeters of the bearing,

And N is the rotation rate in revolutions per minute.

Generally,

There is considerable speed range overlap between bearing types.

Plane bearings typically handle only lower speeds.

Plane element bearings are faster,

Followed by fluid bearings and finally magnetic bearings,

Which are limited ultimately by centripetal force overcoming material strengths.

Play Some applications apply bearing loads from varying directions and accept only limited play or slop as the applied load changes.

One such source of motion is gaps or play in the bearing.

For example,

A 10mm shaft and a 12mm hole has 2mm play.

Allowable play varies greatly depending on the use.

As an example,

A wheelbarrow wheel supports radial and axial loads.

Axial loads may be hundreds of Newtons force left or right,

And it is typically acceptable for the wheel to wobble by as much as 10mm under the varying load.

In contrast,

A lathe may position a cutting tool to plus or minus 0.

002mm using a ball lead screw held by rotating bearings.

The bearings support axial loads of thousands of Newtons in either direction and must hold the ball lead screw to plus or minus 0.

002mm across that range of loads.

Stiffness A second source of motion is elasticity in the bearing itself.

For example,

The balls in a ball bearing are like stiff rubber and under load deform from round to a slightly flattened shape.

The race is also elastic and develops a slight dent where the ball presses on it.

The stiffness of a bearing is how the distance between the parts which are separated by the bearing varies with applied load.

With rolling element bearings,

This is due to the strain of the ball and race.

With fluid bearings,

It is due to how the pressure of the fluid varies with the gap.

When correctly loaded,

Fluid bearings are typically stiffer than rolling element bearings.

Service life Fluid and magnetic bearings Fluid and magnetic bearings can have practically indefinite service lives.

In practice,

There are fluid bearings supporting high loads in hydroelectric plants that have been in nearly continuous service since about 1900 and which show no signs of wear.

Rolling element bearings Rolling element bearing life is determined by load,

Temperature,

Maintenance,

Lubrication,

Material defects,

Contamination,

Handling,

Installation,

And other factors.

These factors can all have a significant effect on bearing life.

For example,

The service life of bearings in one application was extended dramatically by changing how the bearings were stored before installation and use.

As vibrations during storage caused lubricant failure even when the only load on the bearing was its own weight,

The resulting damage is often false brinling.

Bearing life is statistical.

Several samples of a given bearing will often exhibit a bell curve of service life,

With a few samples showing significantly better or worse life.

Bearing life varies because microscopic structure and contamination vary greatly,

Even where macroscopically they seem identical.

L10 Life Bearings are often specified to give an L10 life.

Outside the US,

It may be referred to as a B10 life.

This is the life at which 10% of the bearings in that application can be expected to have failed due to classical fatigue failure and not any other mode of failure like lubrication,

Starvation,

Wrong mounting,

Etc.

Or alternatively,

The life at which 90% will still be operating.

The L10 life of the bearing is theoretical life and may not represent service life of the bearing.

Bearings are also rated using C0 static loading value.

This is the basic load rating as a reference and not an actual load value.

Plain Bearings For plain bearings,

Some materials give much longer life than others.

Some of the John Harrison clocks still operate after hundreds of years because of the lignum vitae wood employed in their construction,

Whereas his metal clocks are seldom run due to the potential wear.

Flexure Bearings Flexure bearings rely on elastic properties of a material.

Flexure bearings bend a piece of material repeatedly.

Some materials fail after repeated bending,

Even at low loads,

But careful material selection and bearing design can make flexure bearing life indefinite.

Short Life Bearings Although long bearing life is often desirable,

It is sometimes not necessary.

Harris 2001 describes a bearing for a rocket motor oxygen pump that gave several hours life,

Far in excess of the several tens of minutes life needed.

Composite Bearings Depending on the customized specifications,

Backing material,

And PTFE compounds,

Composite bearings can operate up to 30 years without maintenance.

Oscillating Bearings For bearings which are used in oscillating applications,

Customized approaches to calculate L10 are used.

External Factors The service life of the bearing is affected by many parameters that are not controlled by the bearing manufacturers.

For example,

Bearing mounting,

Temperature,

Exposure to external environment,

Lubricant cleanliness,

And electrical currents through bearings,

Etc.

High frequency PWM inverters can induce currents in a bearing,

Which can be suppressed by the use of ferrite chokes.

The temperature and terrain of the microsurface will determine the amount of friction by the touching of solid parts.

Tightened elements and fields reduce friction while increasing speeds.

Strengths and mobility help determine the amount of load the bearing type can carry.

Alignment factors can play a damaging role in wear and tear,

Yet overcome by computer aid signaling and non-rubbing bearing types such as magnetic levitation or airfield pressure.

Bearing There are many methods of mounting bearings,

Usually involving an interference fit.

When press fitting or shrink fitting a bearing into a bore or onto a shaft,

It's important to keep the housing bore and shaft outer diameter to very close limits,

Which can involve one or more counterboring operations,

Several facing operations,

And drilling,

Tapping,

And threading operations.

Alternatively,

An interface fit can also be achieved with the addition of a tolerance ring.

Maintenance and lubrication Many bearings require periodic maintenance to prevent premature failure,

But many others require little maintenance.

The latter include various kinds of polymer,

Fluid,

And magnetic bearings,

As well as rolling element bearings that are described with terms including sealed bearing and sealed for life.

These contain seals to keep the dirt out and the grease in.

They work successfully in many applications,

Providing maintenance-free operation.

Some applications cannot use them effectively.

Non-sealed bearings often have a grease fitting for periodic lubrication with a grease gun or an oil cup for periodic filling with oil.

Before the 1970s,

Sealed bearings were not encountered on most machinery,

And oiling and greasing were a more common activity than they are today.

For example,

Automotive chassis used to require lube jobs nearly as often as engine oil changes,

But today's car chassis are mostly sealed for life.

From the late 1700s through the mid-1900s,

Industry relied on many workers called oilers to lubricate machinery frequently with oil cans.

Industry machines today usually have lube systems in which a central pump serves periodic charges of oil or grease from a reservoir through lube lines to the various lube points in the machine's bearing surfaces,

Bearing journals,

Pillow blocks,

And so on.

The timing and number of such lube cycles is controlled by the machine's computerized control,

Such as PLC or CNC,

As well as by manual override functions when occasionally needed.

This automated process is how all modern CNC machine tools and many other modern factory machines are lubricated.

Similar lube systems are also used on non-automated machines,

In which case there is a hand pump that a machine operator is supposed to pump once daily for machines in constant use,

Or once weekly.

These are called one-shot systems from their chief selling point,

One pull on one handle to lube the whole machine,

Instead of a dozen pumps of an alamite gun or oil can in a dozen different positions around the machine.

The oiling system inside a modern automotive or truck engine is similar in concept to the lube systems mentioned above,

Except that oil is pumped continuously.

Much of this oil flows through passages drilled or cast into the engine block and cylinder heads,

Escaping through ports directly onto bearings and squirting elsewhere to provide an oil bath.

This oil pump simply pumps constantly,

And any excess pumped oil continuously escapes through a relief valve back into the sump.

Many bearings in high cycle industrial operations need periodic lubrication and cleaning,

And many require occasional adjustment,

Such as preload adjustment,

To minimize the effects of wear.

Cleaning life is often much better when the bearing is kept clean and well lubricated.

However,

Many applications make good maintenance difficult.

One example is bearings on the conveyor of a rock crusher are exposed continually to hard abrasive particles.

Cleaning is of little use because cleaning is expensive,

Yet the bearing is contaminated again as soon as the conveyor resumes operation.

Thus,

A good maintenance program might lubricate the bearings frequently,

But not include any disassembly for cleaning.

The frequent lubrication by its nature provides a limited kind of cleaning action by displacing older grit-filled oil or grease with a fresh charge,

Which itself collects grit before being displaced by the next cycle.

Another example are bearings in wind turbines,

Which makes maintenance difficult since the nacelle is placed high up in the air in strong wind areas.

In addition,

The turbine does not always run and is subjected to different operating behavior in different weather conditions,

Which makes proper lubrication a challenge.

Packing Some bearings use a thick grease for lubrication,

Which is pushed into the gaps between the bearing surfaces,

Also known as packing.

The grease is held in place by a plastic,

Leather,

Or rubber gasket,

Also called a gland,

That covers the inside and outside edges of the bearing race to keep the grease from escaping.

Bearings may also be packed with other materials.

Historically,

The wheels on railroad cars used sleeve bearings packed with waste or loose scraps of cotton or wool fiber soaked in oil,

Then later used solid pads of cotton.

Ring Euler Bearings can be lubricated by a metal ring that rides loosely on the central rotating shaft of the bearing.

The rings hang down into a chamber containing lubricating oil.

As the bearing rotates,

Viscous adhesion draws oil up the ring and onto the shaft,

Where the oil migrates into the bearing to lubricate it.

Excess oil is flung off and collects in the pool again.

Splash Lubrication A rudimentary form of lubrication is splash lubrication.

Some machines contain a pool of lubricant in the bottom,

With gears partially immersed in a liquid,

Or crank rods that can swing down into the pool as the device operates.

The spinning wheels fling oil into the air around them,

While the crank rods slap at the surface of the oil,

Splashing it randomly on the interior surfaces of the engine.

Some small internal combustion engines specifically contain special plastic flinger wheels,

Which randomly scatter oil around the interior of the mechanism.

Pressure Lubrication For high-speed and high-power machines,

A loss of lubricant can result in rapid bearing heating and damage due to friction.

Also in dirty environments,

The oil can become contaminated with dust or debris that increases friction.

In these applications,

A fresh supply of lubricant can be continuously supplied to the bearing and all other contact surfaces,

And the excess can be collected for filtration,

Cooling,

And possibly reuse.

Pressure Oiling Pressure oiling is commonly used in large and complex internal combustion engines in parts of the engine where directly splashed oil cannot reach,

Such as up into overhead valve assemblies.

High-speed turbochargers also typically require a pressurized oil system to cool the bearings

Reviews

This topic was more interesting than I expected. I listened to the entire thing. I enjoy listening to your podcast because it usually sends me into a peaceful slumber. But occasionally, I discover an unexpected jewel like this that teaches me something that I didn’t realize that I needed to know. It’s well worth the time spent when this happens. It’s rarely a great insight, but like this topic, it’s interesting and helpful information. I knew a little about hinges, joints, and ball bearings, but this helped fill in the gaps. Thanks, Benjamin. 😆

Love this one, too!
I was feeling that it was going to be a wakeful night, put on this podcast for its first run.
I was asleep within minutes, and I learned nothing about hinges.
Perfect! Thank you again, Benjamin!

Who knew that there was so much information on hinges???🤔 Certainly not me! I was out in 10 minutes flat!😉😴😴😴 Thank you Ben!!

These stories are the BEST!! Thanks for boring me to sleep every night!

Absolutely unintelligible. One of your best and it 100% works for me every time within a few minutes! How you made it through recording it without wanting to cry, I have no idea. 😊 Thanks so much!

You can’t beat hinges and ball bearings for putting me to sleep. 💤

Man talk about putting you to sleep. Hahahaha!!! Have a great voice though!!! Thanks tons!!!

Thank you! Terribly boring but it put me to sleep! Who knew that there was so much to know about hinges? 😂😂