Couplings Clutches Flashcards
What is the purpose of a shaft coupling?
Power transmission components used to connect the driving and driven shafts end to end.
What are the 3 types of couplings?
Rigid
Flexible
What are the different types of rigid couplings?
Sleeve couplings
Compression couplings
Ribbed couplings
Flange faced couplings
Threaded couplings
What application would sleeve couplings be used?
Low speed and low torque applications
Very simple ridged coupling
What applications are compressions couplings used?
Light to moderate loads
Can connect two shafts of different diameter
Often used when couplings are frequently removed
When are ribbed couplings used?
Heavy load and torque applications
Fits shafts 1” to 7”
After installation gap should be equal on both sides
Where would a rigid multi bore coupling be used?
Vertical pumps to connect shafts of unequal diameter
Describe flange faced couplings?
Can connect shafts of same or different diameter shafts
Flange halves are made with male and female hubs
Must be aligned properly
When is a threaded coupling used?
Vertical pumps where the drive unit is connects to the pump by a series of drive shafts.
On long applications a steady bearing must be used
What is the most common type of coupling? Why?
Flexible couplings
Because they compensate for some misalignment
How are flexible couplings classified?
Mechanical flexibility
Material flexibility
Combination flexibility (material and mechanical)
What are the types of mechanically flexible couplings?
Roller chain
Silent chain
Synthetic chain
Gear
What are the pros and cons of chain couplings?
Con: Limited torsional, shock and vibration dampening abilities
Must be lubricated to prolong life
Needs to be shielded in dirty environments
Pro:
Very easy to disconnect
Some shaft misalignment and shaft end play is accommodated
Axial travel can be up to 1/4” in some cases
This chain coupling provided more end play than double strand roller chain coupling?
Single roller coupling
This chain coupling is good for smooth running up to 5000rpm?
Silent chain coupling
Allows very minor misalignment and end play
This chain coupling is used for light power where it is not desirable to have oil or dirt?
Synthetic chain coupling
This rigid coupling allows considerable axial float and some angular and offset misalignment?
Gear coupling
What are the characteristics of gear couplings?
Can transmit extremely high torque loads at high rpm
Have mechanical flexibility
When curved teeth are used more misalignment can be tolerated
Can allow for considerable axial movement without transmitting axial thrust to machine components
These couplings are designed to allow parts of the coupling to flex when it’s subject to misalignment, load changes, and shock loads?
Flexible couplings
What are the different types of flexible couplings?
Rubber tire coupling
Elastomeric coupling
Pin and biscuit coupling
Flexible metal disc coupling
This flexible coupling is used to reduce shock and vibration from either the driver or driven machine. It has excellent flex ability that allow for any type of misalignment and end float?
Rubber tire coupling
This flexible coupling is compact and rugged and it’s major advantage is that the flexible element can easily be replaced without disturbing the hubs?
Elastomeric coupling
This flexible coupling uses a rubber or neoprene gasket to allow considerable deflection, torsional flexibility and axial float?
Pin and biscuit coupling
This flexible coupling uses a series of thin steel plates to provide flexibility. It can be used in single or dual disc sets. When dual disc sets are used it can compensate for both angular and oddest misalignment?
Metal disc coupling
What are the most common types of material/mechanical flexible couplings?
Steel grid coupling
Jaw and spider coupling
Splined rubber coupling
Pin and disc connector coupling
Pin and rubber busing connector
This combination coupling allows for torsional flexibility and minor amounts of misalignment. Allows some axial motion and steel grid can be removed easily to disconnect the machines or replace the grid?
Steel grid coupling
These couplings are on small to medium HP applications. To change the spider you must slide one or both of the hubs back?
Jaw and spider coupling
This combo coupling has hub flanges with internal teeth that engage a flexible rubber sleeve. It has high torsional flexibility and can tolerate shock loads, reversing, and dampen vibration.
It allows some shaft misalignment but tolerates considerable axial movement.
Requires no lube and can be used in the food industry
Splined rubber coupling
This combination coupling has a high torsional flex ability, dampens vibration, tolerates shock loads and reversing.
Hubs are either keyed to the shaft or taper locked
A flexible disc is positioned to engage with the pins in the hubs.
Allows for minor amounts of misalignment
Pin and disc connector coupling
This coupling consists of cast iron or steel flanged hubs. One hub is fitted with a number of steel studs or pins with rubber or synthetic bushings mounted to the pins.
Not recommended for drives with much misalignment but works well on reversing drives and can compensate for some axial end float between machine shafts
Pin and rubber bushing coupling
What are some types of special purpose couplings?
Universal joint
Centrifugal coupling
Shear pin coupling
Floating shaft coupling
Spacer coupling
Brake wheel coupling
What is the difference between a single and double universal joint?
Single universal joint can only be at an angle with no parallel offset. Limited to low forces low operating speeds and small angles
Double universal joint works where there is angular and parallel offset. Can be made telescopic
When using a double universal joint what must match?
Angles must be equal on both parts
And
Yokes must be in phase
This joint is used where angles are uneven. Often scene on 4x4 vehicles?
Constant velocity joint (CV joint)
What power transmission characteristics do centrifugal couplings have?
Soft start
Smooth acceleration
Overload protection
Dampening shock
What are the two operating members of a fluid coupling?
Impeller (pump)
Turbine (runner)
How much fluid is recommended for manually filled fluid couplings?
80 percent
True or false? Fluid couplings cannot handle any misalignment or end float?
True, each end of the coupling is held in close tolerances q
This fluid coupling uses heat treated steel shot in the coupling housing?
Dry shot fluid coupling
What type of coupling uses centrifugal force to move the weighted shoes to move outwards to contact the outer ring and engage the shaft?
Centrifugal shoe coupling
This coupling shears when excessive force is generated?
Shear pin coupling
This coupling allows space between the driving motor and drive component?
Floating shaft coupling
What considerations should be taken when deciding what coupling to use?
Speed of unit
Horsepower requirements
Torque capacities
Shaft size
Space limitations
Installation and removal
Ability to perform correct alignment, vibration and balancing requirements of the machine
Availability of spare coupling parts
At what rpm is it recommended to balance high speed couplings?
Over 3600rpm
What are some high horsepower couplings?
Gear coupling
Universal joints
Silent chain coupling
Flange faced couplings
Flexible metal disc couplings
What couplings are good for low HP applications?
Sleeve couplings
Roller chain couplings
Rubber tire couplings
Steel grid couplings
Jaw and spider coupling
Splined rubber couplings
What are the 3 types of shaft misalignment?
Angular
Parallel offset
Combination of angular and offset
What is the correct way to put a coupling on?
1 rotate shafts to make sure bearings are good
2 correct any problems before coupling is installed
3 inspect shaft fix or replace if necessary
4 measure coupling bore and see how it matches the shaft
5 lubricate shaft
7 read manufactures instructions
8 make sure you have axial movement unless specific scenario cannot have axial movement
How much do you heat a steel hub for an interference fit?
180 degrees f above ambient temperatures for every .001” of interference per inch of hub diameter
What is the purpose of a clutch?
Engage or disengage a driven machine without starting or stoping the prime mover.
Clutches can be used to provide variable speeds, constant torque, limited torque, automatic disconnection and ___________?
Quick starts or stops
What are the different types of clutches?
Positive contact clutches
Friction clutches
Radial friction clutches
Axial friction clutches
Square jaw, spiral jaw and multiple tooth are what type of clutch?
Positive contact clutches
What is the downside of positive contact clutches?
Because they do not allow slippage they cannot be engaged at high speeds.
This positive contact clutch in bi directional, compact, simple and does not generate heat?
Square jaw
Actuation method: mechanical sliding of on jaw by mechanical lever, electric solenoid, pneumatic or hydraulic cylinder
This positive contact clutch is one directional but can be engaged at higher speeds then the square jaw?
Spiral jaw clutch
Actuation method: mechanical sliding of one jaw by a manual leaver, electric solenoid, pneumatic or hydraulic cylinder.
This clutch engages at higher speeds than the other two positive engagement clutches. Can be activated manually or electrically?
Multiple clutch tooth
Actuation method: electric solenoid
Friction clutches depend on _______________ between the clutch surfaces and pressure plates?
Coefficient of friction.
This type of clutch can connect and disconnect the power source at any speed?
Friction clutches
There are two classifications of friction clutches. Radial and ___________
Axial
This catagory of friction clutches relies on contact pressure against a rim and drum? What are they ?
Radial clutches
Expanding shoe
And
Contracting shoe
This category of friction clutch uses contact pressure applied to the face using a friction disc and pressure plate?
Axial clutches
Single disc
Multi disc
And cone
This radial friction clutch is usually mechanically engaged where the shoes are attatched to on shaft and the drum to the other. The shoes expand outward to engage the inner section of the drum?
Expanding shoe clutch
Actuation method: mechanical linkage moved by hand, hydraulic cyl, pneumatic cyl, electrical solenoid
This radial clutch acts opposite to the expanding shoe clutch. The rim with an bladder with shoes attached, when the bladder inflates it it forces the shoes inward?
Contracting shoe clutch
Actuation method: bladder engaged by air or oil
These friction clutches rely on friction discs ( clutch disc and clutch plate) pressure plates and flywheels?
Single friction clutch and
Multiple-disc friction clutch
Actuation method: spring applied and mechanical release
Electromagnetically activated clutches rely on what to engage?
It uses a activated magnetic field that pulls the movable armature with a friction disc mounted on its face
This friction clutch is a cross between radial and axial clutches?
Cone clutch
Actuation method: mechanical linkage, pneumatic, hydraulic, or electric solenoid
Hysteresis, magnetic particle and _______ are the three types of magnetic and electric clutches.
Eddy current
Describe magnetic clutches?
Magnetic clutches are non friction clutches that use electric forces to engage the input shaft and output shafts without any direct mechanical connection.
Can electromagnetic clutches transmit the same amount of torque as a friction mechanical clutch?
No this the downside of electromagnetic clutches
The hysteresis clutch slips when?
The load on the output exceeds the strength of the magnetic field
This magnetic clutch can be used in high speed power transmissions with quick response time by energizing the metal particles to form a link between the input rotor and output housing?
Magnetic particle
Actuation method: electric current on or off
What two magnetic clutches are true Magnetic clutches?
Hysteresis
And
Eddy current
These types of clutches are set with a pre determined amount of pressure and when the load becomes to great the clutch slips until over load is resolved?
Torque limiting clutches
Actuation method: spring loaded
Roller ramp, cam type and _______ are the three types of one-way clutches?
Wrap spring
This one way clutch uses springs and rollers to engage the holding power?
Roller ramp clutch
Actuation method: rotation in correct direction
This one way clutch uses spring loaded cams to engage and dis engage clutch?
Can type (spray) clutch
Actuation: rotation in the correct direction
This one way clutch engages by wrapping a spring around the hubs. When it is wound tight enough the shaft starts to drive. Can be used in extremely low power and moderately large torque loads?
Wrap spring clutch
What is an overrunning clutch?
Two members are designed to drive in one direction relative to each other but lock up in the opposite direction of rotation.
Brakes are used to?
Stop motion of the machine
Control speed and direction
Hold loads
, drum and _______ are the two types of brakes?
Disc
Rotating disc brakes and ________ are the two types of disc brakes?
Stationary disc brakes
Drum brakes come in external and _______?
External:
Block brakes
Band brakes
External shoe brakes
Internal
What are the different methods of brake activation?
Like clutches brakes can be applied by:
Mechanical
Pneumatic
Hydraulic
Electrical
