Saturday
April 19, 2014

Homework Help: Electric Power Tools

Posted by Joe on Thursday, December 15, 2011 at 5:38pm.

I need help with my test, I don't know if they are all right or not. I answered the questions to the best of my ability. My answers are marked with an *.

1. What is the typical no-load speed of a high-speed drill?
A. 1,000 rpm
*B. 2,500 rpm
C. 3,000 rpm
D. 3,500 rpm

2. Why should you be especially careful when removing the brush caps from a circular saw or other power tool with external phenolic brush caps?
A. To prevent scratching the brushes in their holders
B. To prevent deforming the brush holder
*C. To prevent breaking the fragile brush caps
D. To prevent bending the retaining springs

3. Which of the following power tools does NOT use a chuck?
A. Hammer drill
B. Power driver
C. High-torque drill
*D. Power screwdriver

4. What type of bearings are used to support the spindle on most table saws?
A. Sleeve
B. Roller
C. Thrust
*D. Pillow block

5. What type of bearing can be used at a drill's or power driver's spindle to absorb a large load inward against the chuck?
A. Thrust
B. Roller
*C. Ball
D. Sleeve

6. The end of the motor shaft on a router is threaded to accept a
A. chuck.
B. driver.
*C. collet.
D. clamping nut.

7. What is the purpose of the external jumper wire on a variable-speed reversing drill switch?
A. To short the brushes together when the switch is released
B. To short the field windings together when the switch is released
*C. To form one-half of a cross-connection system
D. To carry the ground across the switch to the motor

8. Which one of the following gear types is commonly used on residential-type circular saws?
A. Direct
*B. Spur or helical
C. Bevel
D. Worm

9. What type of clutch is used in a hammer drill to enable or disable the spindle drive's final reduction gearing?
A. Friction disk
B. Steel ball
C. Electric cam
*D. Tapered jaw

10. The device used in an air compressor to provide a one-way path for airflow is a
*A. poppet valve.
B. relief valve.
C. vane.
D. shell.

11. Orbital motion in a sander is created by a
A. direct-drive counterweight.
*B. flexible coupled counterweight.
C. eccentric gear and pin.
D. unbalanced gear drive.

12. What is the purpose of a diode in a cordless drill or power screwdriver?
A. To rectify battery voltage
B. To regulate battery power
*C. To prevent reverse charging of the batteries
D. To provide a reverse direction at the switch

13. The type of motor used on cordless ratchets and other cordless tools is the
A. shaded-pole motor.
B. split-phase motor.
C. universal motor.
*D. permanent-magnet motor.

14. What device or method is used on some types of jigsaws to dampen the vibrations caused by the moving rod or shaft?
A. Elastic mounting of the lower bearing
*B. An eccentric counterweight
C. An offset wobble plate
D. A control block

15. What final electrical test should always be performed on power tools, especially those power tools with a metal case, like circular saws?
*A. A leakage test
B. A current test
C. A motor resistance test
D. A line cord continuity test

16. What device is used on a power tool's universal motor to provide a burnout-proof motor?
A. Fuse
B. Circuit breaker
*C. Thermal protector
D. Current relay

17. How is the light bulb powered in a router circuit?
A. Directly from the AC line cord
B. Indirectly from a switch contact
*C. From a tap on a field coil
D. From a brush holder contact

18. How is the two-speed feature of a DC cordless drill constructed?
A. A two-speed switch selects between resistors connected in series with the motor.
*B. A two-speed switch selects between full battery voltage or a tap in the battery pack.
C. A two-speed switch connects the batteries to two different field windings.
D. The ON/OFF switch has two contacts that are enabled depending upon the amount the trigger is depressed.

19. How are many circular saw motors rated instead of using a horsepower rating?
A. Watts
B. Torque
*C. Amperes
D. Poles

20. What is the major difference between a high-speed and a high-torque drill?
A. Chuck type
B. Line cord gage
*C. Output speed
D. Brush thickness

21. The component that clamps around the rod or shaft of a jigsaw and connects to the eccentric pin and bearing is the
*A. yoke.
B. sleeve.
C. detent plate.
D. plunger.

22. What is the common voltage for a cordless drill battery cell?
A. 1.0 VDC
*B. 1.2 VDC
C. 1.5 VDC
D. 2.0 VDC

23. If the primary gear ratio in a drill is 4:1 and a secondary gear ratio is also 4:1, what is the overall gear ratio of the drill?
A. 4:1
B. 8:1
C. 12:1
*D. 16:1

24. Why are the sensors or encoders used on electronic measuring systems two-channel devices?
A. To prevent the loss of measurement in the event of a channel failure
B. To provide twice the signal strength of single-channel devices
*C. To identify the direction of movement
D. To provide twice the signal voltage of a single channel sensor

25. What part most commonly fails in an electric drill or power driver?
*A. Switch
B. Bearing
C. Field coil
D. Armature

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