Final Flashcards
- In most hydroelectric developments the head and water flow will:
Fluctuate
Intake design has a large effect on:
O velocity
O volume
O head
© all three
A partially clogged trash rack will
cause a decrease in the effective head
Wood stave pipe would probably not be used for
heads above 500 feet
An open conduit system implies
the presence of a free surface
The best canal cross-section from a hydraulic point of view is defined as
the one that has a minimum wetted Perimeter
The least efficient type of high-line conduit is that type which
has the greatest effect on the available head
One of the major advantages of using a pressure tunnel in a power conduit system is that
it permits full use of the available head
Steel pipe is used more extensively than any other type of pipe for penstock construction
because
of the degree of flexibility it offers in satisfying design criteria in all of
the above areas
Positive water-hammer pressure caused by a sudden decrease in the demand for water can be
eliminated by:
O a relief valve
O a pressure-regulator
O a surge tank
© any one of the above
Negative water-hammer pressure is created by:
a sudden increase in the demand for water
Which of the below conditions would probably not cause the water level in the riser of a
differential surge tank to fall?
a load rejection
Pumped storage type of hydroelectric developments implies a capability for.
O improving load factors on inter-connected power system steam plants
O providing a wider range of power system reserve capacity
O improved peak load operation
© all of the above
The best hydraulic rectangular cross-section occurs when : (b=bottom width, y=water depth)
y=b/2
Penstock velocities may range from
6 to 20 ft/sec
Which of the following factors affects the power transmitted by a belt?
Friction force applied by the belt and speed of the belt
Generally, the pitch diameter of a V-belt sheave is ___ the outside diameter
Less than
Among conventional V-belts, the narrowest is designated___ and the widest is designated____
A;E
The advantage of using a group belt instead of multiple belts is that the group is
More uniform
Because of their movable side flanges, spring-loaded adjustable sheaves require
Lubrication
Among the advantages of chain drives over belt drives is the fact that chain drives
Are more efficient
Roller chains include the following parts
roller links, pin links, rollers, bushings
Offset roller chain differs from standard roller chain in that the sidebars are___ on one end of each link
Closer together
A chain sprocket with a hub on both sides is a Type_____ sprocket. A sprocket with a hub on only one side is a Type_____sprocket.
C;B
When you install a roller chain, proper procedure includes
• installing the chain with tension on the driving side only
The working depth of a gear is the distance a gear tooth
extends into the space between the teeth of the mating gear
Calculate the diametral pitch of the gear described below No. of Teeth = 30 Addendum = 0.3 in. Outside Diameter = 15.0 in. Dedendum = 0.5 in. Pitch Diameter = 14.7 in.
2.04
The advantages of helical gears over spur gears include
smooth action
Herringbone gears differ from double-cut helical gears in that they (have)
no gap between the two sets of teeth
 The axial pitch of a worm gear is the linear distance
between the screw threads
The main purpose of a miter-gear box is to change the_____ Its gear ratio is typically about_____ to one
direction of motion; one
The main steps in installing a new foot-mounted gear drive include
aligning the equipment
The mechanical power of a gear drive is based on the_____ of the gear drive
speed and torque limit
The service factor for a gear drive depends in part on the
Duty cycle
In parallel-shaft gear drives, oil is commonly provided to the gears by means of
splash lubrication and pressurized feed
The most important factors in selecting an adjustable-speed drive include the unit’s
maximum power, speed required, and speed range
As you force together the flanges on the input sheave of an adjustable-speed belt drive while it is running, the flanges on the output sheave move_____and the output shaft speed_____
farther apart; increases
An adjustable-speed drive can be controlled by a(n)
gear mechanism, electric motor, or pneumatic piston
The belts used in adjustable-speed drives resemble____ belts. In drives that use chain, the chain is similar to a_____chain
Timing; leaf
To align a new motor with an existing pump using the reverse indicator method, you mount the dial indicator(s) on the coupling flange(s) located on (the) ____shaft(s). Each dial indicator takes readings from the flange(s) mounted on (the)____shafts
both; opposite
When aligning three machines, you can align two of them to the third, unless doing so would
require
lowering one or both below the support base
To align a new motor with an existing pump using the face-rim indicator method, you mount the dial indicator(s) on the coupling flange(s) located on (the) _____shaft(s). Each dial indicator
takes readings from the flange(s) mounted on (the) . ______Shaft(s)
only one; opposite
When aligning two machines joined by a long shaft, you use_____ dial indicators, which you mount on (the)______
two; opposite coupling flanges
What are the advantages of laser alignment equipment over dial indicators?
Easier, faster, more accurate alignment
The two major classifications of jaw couplings are the_____jaw couplings
flexible and rigid
The advantages of a chain coupling include the fact that the chain
can be replaced without disconnecting the coupling hubs
If an overload occurs in a machine driven by a shear-pin coupling, the
Pins break
The special features of limited end-float couplings include the
Thrust plate
Spacer couplings provide certain advantages over ordinary couplings, including the fact that
they
simplify the process of disconnecting a driving shaft from the driven
shaft
The purposes of a clutch include
allowing one device to either be connected to another or to run
independently
When a friction clutch operates, a_____ forced the______
shifting device: plates together or apart
An overrunning Clutch is useful in equipment where the dniven machine might need to
run faster than the motor
An electric clutch should be used with a load that must
start and stop frequently
In a single-impeller fluid clutch, motion is directly transmitted from the drive shaft in which sequence?
Impeller, fluid, clutch housing
In a roller-type adjustable-speed drive, the rollers have a_______ shape. Changes in speed are accomplished by changing the_____of the rollers
conical; angle
Check the book
Which of the following can only be cut on a power hacksaw or horizontal bandsaw?
Round stock
The major advantage of a bandsaw over a hacksaw is that the bandsaw
Makes no wasted motion
When you install the band in a horizontal bandsaw the teeth must point
Downward and to the right
When you set up a light-duty horizontal bandsaw, how will you set the bandspeed?
Change the drive belt position
When preparing to make a cut with a horizontal bandsaw which of the following is the final step you will take?
Move the head control lever to RELEASE
If the vertical bandsaw you use requires solid one-piece guide inserts, you must select a pair of upper and lower inserts to match the
Width and thickness of the band
When you set the blade of a vertical bandsaw, make sure the teeth in your right hand point
Downward
When you approach the end of a cut made on the vertical bandsaw, you should
Reduce the feed pressure
Before you use the vertical bandsaw an essential safety requirement is to make sure that
All guards are in place
Alter you cut apart the band of a vertical bandsaw, how should you clean the band ends before rewelding them?
Sand them
Which of the following is a major feature of the sensitive drill press?
Its feed is directly under operator control
Before you change from one tapered-shank drill bit to another, make sure to
Clean the chips from the shank and spindle
Which type of drilling machine can be used for boring operations?
Radial drill
What is a good rule to follow in planning the order of machining steps?
Plan the order to include as few changes in setup as possible
When securing a workpiece on the drill press table before you tighten the vise jaws, you should
Tap the workpiece lightly to seat it
For holes over .5 in. in diameter, you should use either a______ or a_____
Gear-head drill press; radial drill
You must drill a 5 in. hole in a workpiece of hard cast iron (recommended cutting speed of 70 sfpm). What is a good, approximate spindle speed?
560 rpm
You back a large-diameter drill out of thick stock periodically and clear out chips to avoid
Breaking the drill
If your drill’s cutting edge chips as you begin your project, the most likely cause is a(n)
Excessively high feed rate
When you counterbore a hole, you should use a boring bit with a pilot whose diameter is
The same as the existing hole
The most distinctive feature of a typical precision vise for shaping operations is its
Ability to tilt
Whenever you leave a horizontal shaper, even if the project you are working on is not completed, you must
Remove the cutting tool
To help ensure safe operation, which of the following should you do before you operate a shaper?
Set the transmission on the slowest speed
Which of the following must you do before mounting a workpiece in the shaper vise?
Indicate-in the vise or worktable
When you mount a block-shaped workpiece in a shaper vise, the last step in seating the workpiece is to
Tap the work lightly with a soft mallet
When preparing to use the shaper, which of the following should you do first?
Set the length of stroke
 Calculate the stroke-rate setting for a crank-type horizontal shaper, with a 5-in long workpiece of cold work tool steel (recommended cutting speed: 40 sfpm).
46.6 strokes per minute
What is the actual total overtravel made by the ram in one complete cycle of its stroke when the machine is set up according to recommended guidelines?
3/4 in
An absolutely essential safety precaution to use with shapers is to
Wear eye protection
Which of the following operations is especially well-suited for a horizontal shaper, and is usually not possible to do on any other machine?
Cutting a slot or keyway
All of the following can be finished with a surface grinder EXCEPT
The shoulders on a cylindrical workpiece
An essential requirement for beginning a grinding project is to
Allow enough surplus material for grinding
When you dress and true a grinding wheel, start by lowering the wheel so that the diamond lightly touches its
High point
When grinding a long, rectangular workpiece, your first step is to grind the
Basic flat surfaces
When setting up a workpiece on the surface grinder, which of the following procedures should you do LAST?
Turn on the coolant
What is the recommended allowance for finishing cuts in general-purpose grinding?
0.0005 to 0.001 in.
In order to hold a workpiece securely between centers on a cylindrical grinder, you must
Use pressure from the footstock
Which calculation will give you the approximate rotation speed (rpm) for a workpiece on a cylindrical grinder?
sfpm x 4 ÷ workpiece diameter
When the wheel is wider than the raised surface to be ground, the procedure to use is
Plunge grinding
One feature common to all types of horizontal boring mills is the
Headstock column
An optional component that enables you to bore from several different directions without changing the setup is the
Rotary table
An advantage of the stub boring bar over a line boring bar is that it
Decreases vibration
When using a light-weight boring bar, you need a cutter with a
Large back-rake angle and a large side-rake angle
When you use a dial indicator to measure alignment on finished surfaces, correct alignment is achieved when the dial reading
Remains constant
When you align a workpiece having a premachined hole, and using a dial indicator mounted in the spindle, what you are really checking for is
Concentricity
When setting up a line-boring operation, measurements are usually made from the layout lines to the
Boring bar
If you cannot withdraw the boring bar to check the bore diameter, you may need to use a(n)
Inside calipers
What tool is most practical to use when you must rough bore an especially long work area?
Multiple-point boring tool
Which operation on a boring mill requires the use of a power cross-slide tool head?
Facing
To achieve a cutting speed of 4500 sfpm with a 9-in. grinding wheel, the wheel must rotate at about
1900 rpm
Book 328 4.44
A typical application for a dividing head is the milling of a
Gear
The index holes around the spindle of the dividing head are used in____indexing
Direct
If a dividing head has 24 holes around its spindle nose and you must cut four equally spaced notches in a workpiece, how far must you rotate the spindle between cut?
Six holes
If a dividing head has a 40:1 gear ratio, how many times must you turn the worm to move the spindle one quarter of a complete revolution?
10
How many crank turns are needed to index each of 12 equally spaced cuts on a workpiece? Use
the formula: T=40/N
3 1/3
Suppose indexing a workpiece requires 4 turns of the index crank. You will use a hole circle onthe index plate with how many holes?
20
On a dividing head with a 40:1 gear ratio, one turn of the index crank moves the spindle how many degrees?
9
For simple angular indexing on a 40:1 dividing head, you can use an index plate circle with how
many holes?
54
Compound indexing differs from simple indexing in that you
Turn the index plate itself
Differential indexing is similar to, but more accurate than,____indexing
Compound
What makes a universal dividing head different from a plain dividing head?
Its spindle nose can be swung up 90°
When you use a center in the dividing head spindle to hold a workpiece, you install the other
center in the
Footstock
When mounting work on the dividing head center, you assure a positive flow of power from the dividing head spindle to the workpiece by using a
Driver and milling machine dog
When using a chuck to hold a workpiece on the dividing head, you can give the workpiece extra support with a
Steady rest
If you straddle mill a hexagonal workpiece, how many times must you position the work?
Three
Why should you insert a cap into the opening of the dividing head spindle?
To keep chips out of the spindle
When using the direct indexing method, you should NOT
Count the zero hole
To use the plain indexing method, the worm and worm gearing in the dividing head must be
Engaged
When plain milling, which side of a hexagonal workpiece should you mill after taking the first cut?
The opposite side
The dividing head is useful for drilling holes
In a circle
Cutting the teeth in a spur gear is a type of____milling.
Form
To mill spur gears, you should use ______cutters
Special profile
Compute the outside diameter of a 30-tooth sour gear blank with a diametral pitch of SIx. USE the following formula
OD = N+2/DP
5.333in
Which of the following factors does NOT affect cutter selection for milling spur gears?
Whole tooth depth
Series of eight cutters each have been developed to cut gears with different numbers of teeth that have the same
Diametral pitch
To index the teeth of a large-diameter gear, use a
Rotary table
When measuring a newly cut gear over pins, you should use a
Micrometer
To check spur gear tooth thickness at the pitch circle, use a
Gear tooth vernier caliper
The distance between adjacent helices that are wound on a common cylinder is called the
Helix pitch
The lead of a helix is determined by the
milling machine lead
To mill a helix, you must use change gears to link the lead screw of the milling machine with the
Dividing head worm shaft
If the ratio of change gearing is 1:1 and the lead of the milling machine is 10 in., a helix milling would have a lead of
10in
How many change gears usually make up a set?
Four
In the change gear formula 40/ao × 240 , how many teeth will the two driving gears each have?
40 and 24
In order to reverse the direction of gear rotation so that you can mill either a right- or left-hand helix, use a(n)
Idler gear
When using simple angular indexing to mill 15 teeth into a cylindrical workpiece, how far aprt must you space each tooth?
24°
In order to obtain the proper helix angle when milling a helical workpiece, you must swivel the
Machine table
Which of the following factors is NOT important for you to know about a helical gear you are milling?
Where it will be used
When milling helical gear teeth, you should NOT draw the cutter back through the work after a cut is complete because
You could damage the gear tooth surface
The tooth dimensions of spur gears are described by circular pitch. What measurement do you use to describe helical gear teeth?
Normal diametral pitch
What function does a cam perform?
They change the direction of motion of machine parts
The follower in a nonpositive cam system would NOT be controlled by
A groove in the cam
The distance that one cam lobe moves the follower from its starting point as the cam rotates is the
Cam rise
