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Auto 2 Goosey > Chapter 77 Review > Flashcards

Chapter 77 Review Flashcards

Review of points in chapter 77

1
Q

What are the functions of a steering system?

A
  1. Provide precise control of the front-wheel direction and, sometimes, the rear-wheel direction
  2. Maintain correct amount of effort needed to turn the wheels
  3. Transmit road feel to the driver’s hands
  4. Absorbs most of the shock going to the steering wheel from bumps
  5. Allows suspension action with minimal effect on the direction and alignment of the front wheels
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2
Q

What are the two basic kinds of steering systems used today?

A
  1. Linkage (worm gear)
  2. Rack-and-pinion
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3
Q

What kind of vehicles are linkage steering systems found?

A

Large, full-size pickup trucks and full-size vans, both two- and four-wheel drive

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4
Q

What kind of vehicles are rack-and-pinion steering systems found?

A

Passenger cars and small trucks for being lighter

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5
Q

List the components of a basic linkage (worm gear) steering system

A
  1. Steering wheel
  2. Steering shaft
  3. Steering column
  4. Steering gearbox
  5. Steering linkage
  6. Ball sockets
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6
Q

List the components of a basic rack-and-pinion steering system

A
  1. Steering wheel
  2. Steering column
  3. Steering shaft
  4. Steering pinion gear
  5. Rack
  6. Gear housing
  7. Tie-rods
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7
Q

What makes up the steering column assembly?

A

The steering wheel, the steering shaft, column (outer housing), and sometimes, ignition key mechanism, a flexible coupling, and a universal joint

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8
Q

Where is the steering column bolted?

A

It’s normally bolts to the underside of the dash

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9
Q

What is the assembly of the steering shaft to the column and the steering wheel then to the shaft?

A

Bearings fit between the steering shaft and the column. They let the shaft rotate freely. The steering wheel is splined to the shaft. A large nut holds the steering wheel on the shaft splines. The airbag is fastened to steering wheel

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10
Q

Where are the ignition lock and switch mechanism usually mounted?

A

The steering column in most vehicles, with the ignition lock normally on the top right-hand side of the column and the switch usually is bolted inside the steering column

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11
Q

What feature was implemented in late-model vehicles, in regards to steering, to prevent theft?

A

A locking steering wheel

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12
Q

Explain a common method of locking a steering wheel

A

A rack and a sector are used to slide a steel pin into mesh with slotted disc that is splined to the steering shaft. This locks the steering shaft to the column, preventing the steering wheel from being turned

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13
Q

What is the purpose of a collapsible steering column?

A

To help prevent driver chest and face injury during an accident

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14
Q

What are the different types of collapsible steering columns and how many pieces make it up?

A
  1. Steel mesh (crushing) columns
  2. Tube-and-ball (sliding) columns
  3. Shear capsule (break and slide) columns

In all types, the column is made up of two pieces

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15
Q

What is the purpose of a tilt steering column/tilt steering wheel?

A

To use a flex joint, or U-joint, to allow the top half of the column and the steering wheel to be positioned at different angles

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16
Q

What are the different types of tilt steering columns and their design?

A
  1. Manual tilt column uses a lever on the steering column to unlock the flex joint so the wheel can be moved up or down
  2. Power tilt column uses a small electric motor, a control switch, and a gear mechanism to change steering wheel angle and height
  3. Memory tilt wheels use a tilt control module (computer) to “remember” more than one steering wheel position. A sensor in the steering column provides feedback on the wheel’s position. When the switch is pressed, the control module energizes the power tilt motor to move the wheel to the pre-programmed position
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17
Q

In what type of steering system is the recirculating-ball gearbox used, linkage (worm gear) or rack-and-pinion?

A

Linkage (worm gear). Only linkage steering systems use a steering gearbox

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18
Q

What happens in a recirculating-ball gearbox?

A

It has small steel balls that circulate between the gear members

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19
Q

What are the components of a recirculating-ball gearbox?

A
  1. Worm shaft
  2. Sector shaft
  3. Ball nut
  4. Ball guides
  5. Adjusting nut
  6. Adjusting screw
  7. Gearbox housing
  8. End cover
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20
Q

What is the role of a worm shaft in a recirculating-ball gearbox?

A

Is the input gear connected to the steering column shaft. The balls fit and ride in the grooves in the worm gear. It is mounted in either ball bearings or roller bearings

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21
Q

What is the role of a sector shaft in a recirculating-ball gearbox?

A

Is the output gear from the steering gearbox. It transfers motion to the steering linkage. A sector gear is machined on the inner end of the sector shaft. It is mounted on anti-friction bearings

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22
Q

What is the role of a ball nut in a recirculating-ball gearbox?

A

It rides on the ball bearings and the worm gear. Grooves are cut in the ball nut to match the shape of the worm gear. The ball nut cannot rote, it slides up and down as the worm gear rotates

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23
Q

What is the role of ball guides in a recirculating-ball gearbox?

A

They route extra ball bearings in and out from between the worm and ball nut

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24
Q

What is the role of a bearing adjusting nut in a recirculating-ball gearbox?

A

Is usually provided to set worm shaft bearing preload

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25
Q

What is the role of an adjusting screw in a recirculating-ball gearbox?

A

Is used to set the sector shaft clearance

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26
Q

What is the role of the gearbox housing in a recirculating-ball gearbox?

A

Provides enclosure for the other components. Seals press into it to prevent lubricant leakage at the worm and sector shaft. Shaft bearings press into it as well. It is bolted to the vehicle frame or a reinforced area

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27
Q

What is the role of the end cover in a recirculating-ball gearbox?

A

Normally bolts on the housing to cover the end of the sector gear. It can be removed for gearbox service

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28
Q

What is gearbox/steering ratio?

A

Also called steering gear reduction. It’s a comparison between steering wheel rotation and sector shaft rotation

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29
Q

What is the range of gearbox ratios?

A

15:1 to 24:1

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30
Q

Which type of gearbox has a high gearbox ratio and why?

A

A manual gearbox will have a high gearbox ratio to reduce the amount of effort needed to turn the steering wheel

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31
Q

Which type of gearbox has a low gearbox ratio and why?

A

Power steering gearboxes so that turning front wheels requires less steering wheel rotation for faster steering response

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32
Q

What is the purpose and benefits of a variable-ratio gearbox?

A

It changes the internal gear ratio as the front wheels are turned from the center position. Most modern recirculating-ball gearboxes use variable-ratio design.
It is faster when cornering, requiring fewer turns to move the steering wheel from full right to full left. Also provides better control and response when maneuvering

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33
Q

What is the purpose of a constant-ratio gearbox?

A

It has the same gear reduction from full left to full right than variable-ratio gearbox. The sector gear teeth are the same length

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34
Q

What is a worm-and-roller gearbox?

A

It contains a roller that is mounted on the pinion shaft and meshes with the worm gear. The roller replaces the ball bearings and the ball nut used in the recirculating-ball gearbox. It imparts a rotary force on the pitman shaft as the worm gear rotates. This design reduces internal friction

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35
Q

What is steering linkage?

A

It’s a series of arms, rods, and ball sockets that connect the worm-type steering gearbox to the steering knuckles

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36
Q

What is another name for the steering linkage used in
a worm-type gearbox?

A

Parallelogram steering linkage

37
Q

What are the components of a steering linkage/parallelogram steering linkage?

A
  1. Pitman arm
  2. Center link
  3. Idler arm
  4. Two tie-rod assemblies
  5. Steering damper (may include, not always)
38
Q

What is the purpose of a pitman arm in the steering linkage?

A

It transfers gearbox motion to the steering linkage. It is splined to the gearbox sector (output) shaft. A large nut and lock washer secure them arm to its shaft. The outer end of the the pitman arm is normally connected to the linkage thought a ball socket.

39
Q

What role do ball sockets provides to a pitman arm in the steering linkage?

A

They provide for motion in all directions between two connected parts. They are needed so the steering linkage is not bent and damaged when the wheels turn or move up and down over rough road surfaces. They are filled with grease and reduce friction and wear. Some are sealed, others have a grease fitting to allow chassis grease to the injected

40
Q

What is the purpose of a center link in the steering linkage?

A

It’s also called relay rod. It’s a steel bar that connected the right and left sides of the steering linkage. It has holes that accept the pitman arm, tie-rods, and idler arm

41
Q

What is the purpose of an idler arm in the steering linkage?

A

The idler arm supports the end of the center link on the passenger side.

42
Q

What is the purpose of a steering damper in the steering linkage?

A

It’s an oil-filled shock absorber. It’s attached between the vehicle’s frame and the center link to help absorb road shocks before they reach the steering gear

43
Q

What is the purpose of tie-rod assemblies in the steering linkage?

A

Two tie-rod assemblies fasten the center link to the steering knuckles. Each assembly consists of two tie-rods and a toe adjustment sleeve. Ball sockets are usually used in both ends of each assembly. The one connected to the center link is the inner tie-rod and the one connected to the steering knuckle is the outer tie-rod

44
Q

What is the purpose of the toe adjustment sleeve in a tie-rod assembly in the steering linkage?

A

It’s provided for changing the length of the tie-rod assembly during wheel alignment

45
Q

What is the purpose of the flexible coupling in rack-and-pinion steering?

A

It helps keep road shock from being transmitted to the steering wheel. Also, allows for slight misalignment of the steering shaft and steering gear input shaft (pinion shaft)

46
Q

What is the purpose of a universal joint in rack-and-pinion steering?

A

It allows for a change in the angle between the steering column and steering shaft

47
Q

What are the components of a rack-and-pinion steering gear?

A
  1. Pinion shaft
  2. Rack
  3. Thrust spring
  4. Bearings
  5. Seals
  6. Gear housing
48
Q

Where is the rack-and-pinion steering gear attached?

A

It is bolted to the vehicle’s frame or unibody structure. It uses large bolts with rubber bushings to secure the unit and help absorb road shock

49
Q

How do the the pinion shaft and rack work together in a rack-and-pinion steering gear assembly?

A

When the steering shaft turns the pinion shaft, the pinion gear acts on the rack gear. The rack then slides sideways inside the gear housing. Either bushings or roller bearings may be used in either. Frequently, the pinion shaft uses roller bearings and the rack uses plain bushings

50
Q

How is the purpose of the thrust spring in a rack-and-pinion steering gear assembly?

A

It preloads the rack-and-pinion gear teeth to prevent excessive gear backlash (play). Adjustment screws or shims may be used to set thrust spring tension

51
Q

What do tie-rod assemblies connect in a rack-and-pinion steering system?

A

They connect the ends of the rack with the steering knuckles

52
Q

Describe the construction of the tie-rods used in a rack-and-pinion steering assembly

A

A very large ball formed on one end of each inner tie-rod fits into a socket that screws onto the end of the rack. A conventional. Rubber dust boots fit over the inner ball sockets to keep out road dirt and water, as well as hold in lubricating grease. Clamps secure each end of the dust boots

53
Q

How do power steering systems get power?

A

They normally use an engine-driven pump and a hydraulic system to assist steering action. They can also use an electric motor in the rack to provide power assist

54
Q

How do power steering systems work?

A

Pressure from an oil pump is used to operate a piston-and-cylinder assembly. When the control valve routes oil pressure into one end of the piston, the piston slides in its cylinder. Piston movement can then be used to help move the steering system components and the front wheels of the vehicle

55
Q

What are the major types of power steering systems used on modern automobiles?

A
  1. Integral-piston linkage systems
  2. External cylinder power steering systems
  3. Power (hydraulic or electric) rack-and-pinion systems

The rack-and-pinion system can be further divided into the integral and the external power piston systems.

The integral rack-and-pinion power steering system is the most common

56
Q

What is the purpose of the power steering pump?

A

It’s engine driven and produces the hydraulic pressure for steering system operation. In most cases, a belt running from the engine crankshaft pulley powers the pump

57
Q

What are the basic types of power steering pumps?

A
  1. Roller
  2. Vane
  3. Slipper
  4. Gear
58
Q

What is the purpose of the power steering fluid reservoir?

A

It holds an extra supply of power steering oil or fluid. It can be formed as part of the pump body or it can be a separate container.

59
Q

How does a power steering pump work to provide the assistance give by power steering?

A

During a pump operation, the drive belt turns the pump shaft and pumping elements. Oil is pulled into one side of the pump by vacuum. The oil is then trapped and squeezed into a smaller area inside the pump. This pressurizes the oil at the output, causing it to flow to the rest of the power steering system.

60
Q

What is the purpose of the pressure-relief valve in a power steering assembly?

A

It’s used to control maximum oil pressure. It prevents system damage by limiting pressure when needed

61
Q

What is the purpose of power steering hoses in a power steering assembly?

A

They are high-pressure hydraulic, synthetic hoses that connect the power steering pump and the integral gearbox or the power cylinder. One line serves as the pressure feed line, and the other acts as a return line to the reservoir. Metal lines are also used when vibration or part movement is not a problem

62
Q

What is the setup of an integral-piston power steering system?

A

It has the hydraulic piston mounted inside the steering gearbox housing. It consists of a power steering pump, hydraulic lines, and an integral power-assist gearbox

63
Q

What is in an integral power steering gearbox?

A

It contains a conventional worm-and-sector gear, a hydraulic piston, and a flow-direction valve

64
Q

What are the types of valves used in an integral power steering gearbox?

A
  1. Spool valve
  2. Rotary valve
65
Q

How does a spool valve-type power steering gearbox work?

A

It uses a small spool valve to control the pressure entering the power assist chambers. When the steering wheel is turned to the right, the pivot lever moves the spool valve so that pressure enters the right-turn chamber. This forces the power piston to the left and helps turn the sector shaft for a right turn. It’s the opposite if turning left.

66
Q

How does a rotary valve-type power steering gearbox work?

A

It has a small torsion bar to detect steering wheel turning direction and turning effort. When the steering wheel is turned, the torsion bar twists and turns the rotary valve, which then directs hydraulic pressure to the correct side of the power piston

67
Q

What is an external cylinder power steering system?

A

In it the power cylinder is commonly bolted to the frame and center link. The control valve may be located in the gearbox or on the steering linkage. It is found on older passenger cars and large industrial equipment but has been phased out for more compact arrangements

68
Q

How does power rack-and-pinion steering work?

A

It uses hydraulic pump pressure to assist the driver in moving the rack and the front wheels. The power steering pump is normally mounted in the front of the engine. A drive belt powers the pump. Power steering hoses and metal lines connect the pump with the rack-and-pinion gear assembly

68
Q

What is the power cylinder in a power rack-and-pinion assembly?

A

Is a hydraulic cylinder machined inside the rack or gear housing. It is a precisely machined tube designed to accept the power piston

68
Q

What are the components of a power rack-and-pinion assembly?

A
  1. Power cylinder
  2. Power piston
  3. Hydraulic lines
  4. Control valve

Other parts of the assembly are similar to those that are found on a manual rack-and-pinion assembly

69
Q

What is the power piston in a power rack-and-pinion assembly?

A

Is a hydraulic double-acting piston formed on the rack shaft. It is formed by attaching a hydraulic piston to the center of the rack. A rubber seal fits around a groove in the piston to prevent oil pressure leakage. Seals are also used on each end of the piston to keep fluid from leaking into the boots

70
Q

What are the types of control valve mechanisms used on power rack-and-pinion gears?

A
  1. Rotary control valves
  2. Spool control valves

Rotary being more common

71
Q

How does the rotary control valve work in a power rack-and-pinion gears?

A

It operated by a torsion shaft connected to the pinion gear

72
Q

How does the spool control valve work in a power rack-and-pinion gears?

A

The thrust action of the pinion shaft shifts the spool control valve. The control valve can then route oil to the power cylinder

73
Q

How does a power-rack-and-pinion setup operate?

A

When the steering wheel is turned, the weight of the vehicle causes the front lines to resist turning. This twists a torsion bar (rotary valve) or thrusts the pinion shaft (spool valve) slightly, making the valve move and align specific oil passages. Pump pressure flows through the control valve, through hydraulic line, and into the power cylinder. Pressure then acts on the power piston, which helps push the rack and the front wheels for turning

74
Q

What is the purpose of a power steering oil cooler?

A

Used to remove excess heat from the oil. It is usually a small mental line or radiator located in one of the power steering lines

75
Q

What makes the electronic steering assist different from other power steering systems?

A

It uses a small electric motor to help move the rack-and-pinion gearbox. The motor is mounted inside the rack housing or on the steering column. Motor acts directly on the steering rack or steering column shaft

76
Q

What are the benefits of an electronic steering mechanism?

A

It eliminates the need for hydraulic steering assist and the bulky power steering pump, hoses, and hydraulic cylinder

77
Q

What is a different design of electronic steering assist?

A

It has a small electric drive motor, gearbox, clutch, and control circuit mounted inside the steering wheel. The assembly is mounted inside the center section of the steering wheel, underneath the driver airbag. The power steering motor applies power assist directly to the top of the steering shaft.

78
Q

What does proportional rack-and-pinion power steering do? and what other names does it have?

A

It senses vehicle speed and steering load to ensure adequate road feel. It is also called speed-sensitive power steering

79
Q

How do proportional steering systems function?

A

They alter steering wheel effort as road speed changes. They increase effort at higher speeds for more road feel. They also lower steering effort at low speeds to help the driver turn the steering wheel when parking

80
Q

How do proportional rack-and-pinion power steering with a computer-controlled electromagnet work?

A

It is mounted around the steering gear stub shaft. The stub shaft acts on a small torsion bar. The stub shaft and torsion bar operate the power steering valve, which controls fluid flow to the rack for power assist. If the vehicle is not moving or is moving slowly, an electronic control module (computer) sends current through the electromagnet in one direction to help attract and pull on the stub shaft and torsion bar, increasing valve output pressure to make the vehicle easier to steer. When the vehicle reaches road speed, the module reverses electrical flow through the electromagnet to increase steering effort to improve road feel

81
Q

How do proportional rack-and-pinion with stepper motor or solenoid work?

A

The computer-operated steeper motor or solenoid helps shift the fluid valve to affect steering effort. The stepper motor is not as smooth or as variable as the electromagnetic-assist system

82
Q

How do four-wheel steering systems differ from two-wheel?

A

Instead of just the front two wheels, all four wheels change direction to improve handling, stability, feel, and maneuverability

83
Q

What are the different types of four-wheel steering systems?

A
  1. Mechanical
  2. Hydraulic
  3. Electronic
84
Q

How does the mechanical four-wheel steering system work?

A

It uses a special front rack-and-pinion gearbox with a transfer box. The transfer box operates a long shaft that extends back to the rear rack. When the front wheels are turned, the shaft rotates to turn the read wheels. It was the first four-wheel steering system on the market

85
Q

How does the hydraulic four-wheel steering system work?

A

It uses a conventional power rack-and-pinion steering system up front. A vane pump forces fluid to the rack to provide power assist. Hydraulic lines extend back to a rear power steering pump, which is driven by the differential. Depending on vehicle speed, the rear pump forces fluid under pressure into a control valve. The control valve can operate the rear steering system after reaching a specific speed. The rear rack tie-rod ends are attached to the suspension system’s trailing arm. When activated, the rack shifts the trailing arm to steer the rear wheels

86
Q

How does the electronic four-wheel steering system work?

A

It has an electric motor-driven power rack that acts upon the rear wheels via its own recirculating ball drive and mechanical links. An electronic control module controls rear-wheel steering angles. The module analyzes signals from angle sensors in the front steering, from wheel speed sensors in the anti-lock brake system, and from a yaw sensor. The motor-driven power rack is then energized by the module to move the rear wheels as needed.

87
Q

What happens to the rear wheels when making a slight turn of the steering wheel on four-wheel drive? What about when it’s a sharp turn?

A

The rear wheels turn in the same direction as the front wheels for a slight turn of the steering wheel. For a sharp turn, the special gearbox straightens out the rear wheels and then turns them in the opposite direction of the front wheels

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