Couplings, Clutches and Brakes Flashcards
What are the 4 basic types of couplings
Rigid, Flexible, U-joints, Cetrifugal
What are the 3 types of misalignment
Angular, Parallel (offset), Axial
This coupling is a long, heavy-walled tube with a precision bore and a keyway cut along the the length
Sleeve coupling (low speed, low torque)
Types of rigid flange couplings
Spigot and recess (keyed), Compression (no keys)
Can be same size or different diameter shafts
Clamp (muff) couplings are for high or low speed drives?
Low speed (unbalanced weight), heavy load and torque
What are the 3 types of Flexible couplings
Mechanically, elastomeric, universal
Couplings of this type get their flexibility from the sliding or rolling of mating parts and usually require lubrication
Mechanically flexible
This flexible coupling is composed of two jawed hubs and a slider block between them. Designed for low speed and high torque
Jaw and slider (allow for angular and offset misalignment)
This coupling have two hubs with curved external teeth joined by an outer member with internal teeth
Gear-type double engagement (can operate at high speeds)
Gear-type couplings allow for angular misalignment of this many degrees
1.5 degrees
What types of chain are available for chain couplings
Roller (moderate speed), silent (heavy duty drives up to 5000rpm), and synthetic (light power)
In these couplings multi-grooved flanges hold a flat steel grid what weaves in and out through grooves
Metallic grid
These metallic couplings need no lubrication, are double-engagement and allow high-speed operation and are well balanced
Metallic disk (no backlash permitted)
This coupling uses elastomeric elements called spiders
Jaw elastomeric (lovejoy)
These couplings transmit torque through shear loading of the elastomer
Unclamped doughnut coupling
These couplings have an elastomeric, split doughnut with metal inserts permanently moulded into them
Clamped doughnut couplings
These couplings have a flexing element with reinforcement at the outermost radii
Clamped tire coupling
These couplings are used to connect high-inertia drives to low-inertia driven members
Bushed pin coupling (diesel engine to hydrostatic pump)
High rotational speeds
These couplings accommodate large amounts of offset alignment without creating side load on the shafts
Offset coupling
These are used to accommodate shafts which have misalignment greater than flexible couplings allow
U-joints
A single U-joint is used to connect shafts with this type of misalignment
Angular
Two U-joints are used to connect shafts with this type of misalignment
Angular and/or offset (U-joints cannot accommodate axial misalignment (end play)
The recommended maximum shaft angles for a U-joint
15 degrees below 100 rpm, up to 45 degrees (5 degrees minimum)
The two simplest types of U-joints
Block and pin, cross-and-bearing
The 3 types of centrifugal couplings
Mechanical (clutch-style), hydraulic (fluid coupling), dry fluid
Allowing the prime mover to reach a set rotational speed before applying the load of driven equipment is known as this
A soft start
This safety device trips a switch when the coupling reaches a critical temperature
Thermal cutout
In this type of coupling centrifugal force causes weights to press friction material against a drum to transmit power
Clutch-style
These couplings have a impeller and turbine (runner)
Fluid coupling
This occurs at start-up when the impeller is turning and the turbine is not moving
High vortex
This occurs when the impeller and turbine run at almost equal speeds
Low vortex
Torque development in this coupling depends on the amount of fluid available in the working section
Constant fill
This type of fluid coupling uses a reservoir and offers excellent overload protection
Delayed fill
This fluid coupling uses an external lever
Variable fill
At this many rpm centrifugal lockup couplings are mechanically linked 1:1
850 rpm (called lockup)
These couplings have in their housings a single rotor and a predetermined amount of heat-treated metal shot
Dry fluid (shot) couplings
The shot in a dry coupling is called this
flow charge
The two categories of clutches
Mechanical and electromagnetic
This type of mechanical clutch has square teeth that lock into mating recesses in facing members
Square jaw (engage at up to 10 rpm)
This type of mechanical clutch has sloped on one side of the jaw for easy engagement
Spiral jaw (engage at up to 150 rpm)
This mechanical clutch have two mating rings with a large number of small teeth or serrations
Multi-tooth (engage up to 300 rpm)
The two mating surfaces of a friction clutch or brake
Cast iron as a disk, band or drum. Other surface is a friction facing of moulded organic material bound by heat-cured resin (plate, pad, or shoe)
This is a protective device that limits the torque transmitted to the equipment
Torque limiter
The two types of drum units
Constricting and expanding
These clutches are units which allow unidirectional power transmission
Over-running
These clutches have pieces composed of two non-concentric curves of different radius
Sprag
In these clutches the input and output shafts are connected by a coiled spring
Wrap spring (ID of spring slightly smaller than OD of shaft hubs)
These clutches transmit torque through rollers that ride on the ramped or cammed surface
Roller-ramp
The three basic types of electromagnetic clutches and brakes
Magnetic particle, eddy current, hysteresis
This electromagnetic clutch/brake has dry iron particles fill the space between input and output members
Magnetic particle (good for continuous changes of speed)
These clutches have an input drum, a stationary field coil, and an output rotor
Eddy current (not used to hold a load)
In this clutch a coil generates a magnetic field in the input rotor and in the output element called a drag cup
Hysteresis (used in fractional horsepower applications)
Methods of actuation for clutches and brakes
Mechanical, electrical, pneumatic, hydraulic, self-activating
The simplest cheapest way to engage clutches and brakes
Mechanical
An electromagnetic clutch or brake has two basic parts
annular electromagnet (coil), and an armature
The most frequent method of actuation for clutches and brakes in industrial equipment
Pneumatic (up to 200 psi)
This type of actuation actuates and releases because of differences in speed or direction of rotation
Self-activating
This is a special type of coupling commonly used on applications such as vertical pumps
Threaded couplings
The axial travel for a chain coupling can be up to this
1/4”
A smaller more compact version of the rubber tire coupling
Bonded rubber type
These joints are used when the joint angles are uneven
Constant velocity joints (CV joints)
The amount of slip on a fluid coupling can be between this percentage
2-6%
Fluid couplings use these in the couplings housing if an overload continues
Fusible plugs (sometimes uses a switch that can be triggered)
Fluid couplings should be filled to a maximum of this percentage of their total capacity
80%
This coupling is used where the drive component cannot be located close to the driving motor
Floating shaft coupling (spool)
Couplings over this many rpm’s need to be dynamically balanced
3600 rpm
The gap between halves on a split rigid coupling should be this much
1/16” to 1/8”
Cone clutch engagement angles
10-15 degrees
Silent chain couplings are for speeds up to
5000 rpm
The amount of axial movement on a metallic grid coupling
3/16” on a 2 to 4 inch diameter coupling
How hot should you heat the coupling for a shrink fit
180F above ambient temp for every 0.001” of interference per inch of hub diameter
Coupling used for high torque and power applications
Gear coupling Universal joints Silent chain Flange-face Flexible metal disk
Couplings used for low HP
Sleeve Roller chain Rubber tire Steel grid Jaw and spider Splined rubber (unclamped doughnut)
