chap90 pps Automotive technology at University of Cambridge

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chap90 pps  Automotive technology at University of Cambridge

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start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 90, the reader should be able to: • Prepare for ASE Suspension and Steering (A4) • • • certification test content area “A” (Steering System Diagnosis and Service) Identify steering linkage components Describe how the movement of the steering wheel causes the front wheels to turn Describe how to perform a dry park test to determine the condition of steering system components Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 90, the reader should be able to: • • • Perform an under-the-vehicle inspection of the steering system components List the service procedures for under-the vehicle steering system service Explain how to replace steering linkage parts Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: articulation test • ball socket assembly center link • center take-off rack • cross-steer linkage dry park test • front steer • grease fitting opposite-phase steering parallelogram linkage • pitman arm • RBS • rear steer same-phase steering • steering dampener • steering stops • SWPS tie rods • zerk fitting Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The proper operation of the steering system is critical to the safe operation of any vehicle Always follow the service procedures specified by the vehicle manufacturer Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 STEERING LINKAGE The steering linkage relays steering forces from the steering gear  to the front wheels Most conventional steering linkages use the parallelogram­type  design. A parallelogram is a geometric box shape where opposite  sides are parallel and equal distance A parallelogram­type linkage uses four tie rods, two inner and  two outer (left and right), a center link (between the tie rods), and  an idler arm on the passenger side and a pitman arm attached to  the steering gear output shaft (pitman shaft).  See Figure 90–1 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 90–1 Steering movement is transferred from the pitman arm that is splined to the sector shaft (pitman shaft), through the center link and tie rods, to the steeting knuckle at each front wheel The idler arm supports the passenger side of the center link and keeps the steering linkage level with the road (Courtesy of Dana Corporation) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 As the steering wheel is rotated, the pitman arm is moved. The pitman arm  attaches to a center link. At either end of the center link are inboard (inner) tie  rods, adjusting sleeves, and outboard (outer) tie rods connected to the steering  arm. The passenger side of all these parts is supported and held horizontal by an  idler arm that is bolted to the frame.  The center link may be known by several names, including: Center link Connecting link Connecting rod Relay rod Intermediate rod Drag link (usually a truck term only) Other types of steering linkages often used on light trucks and vans  include the cross­steer linkage.  See Figure 90–2.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 90–2 The most common type of steering is the parallelogram The cross-steer and Haltenberger linkage designs are used on some trucks and vans Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: Many light trucks, vans, and some luxury cars use a steering  dampener attached to the linkage. A steering dampener is similar to a  shock absorber, and it absorbs and dampens sudden motions in the steering  linkage.  Figure 90–3 Typical steering dampener used on a Hummer H2 Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman Continued ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Step #3  Replace the part using the hardware and fasteners  supplied with the replacement part. Do not reuse the precrimped  torque prevailing nuts used at the factory as original equipment on  many tie rod ends CAUTION: Vehicle manufacturers often warn not to use a tapered pickle  fork tool to separate tapered parts. The wedge tool can tear the grease seal  damaging both the part being removed and the adjoining part Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 CAUTION: Whenever tightening the nuts of tapered parts such as tie rods, DO NOT loosen after reaching the proper assembly torque to align the cotter key hole. If the cotter key does not fit, tighten the nut further until the hole lines up for the cotter key. Always use a new cotter key Figure 90–36 Align the hole in the tie rod end with the slot in the retaining nut If the holes not line up, always tighten the nut further (never loosen) until the hole lines up Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 When replacing tie rod ends, use the adjusting sleeve to adjust the  total length of the tie rod to the same position and length as the  original. Measure the original length of the tie rods and assemble  the replacement tie rod(s) to the same overall length See Figure 90–37 When positioning the tie rod end(s), check that the stud is centered  in the socket. This permits maximum steering linkage movement  without getting into a bind if the steering linkage is pivoted beyond  the angle the tie rod end can move in the socket See Figure 90–38 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 90–37 Replacement tie rods should be of the same overall length as the originals Measure from the edge of the tie rod sleeve to the center of the grease fitting When the new tie rod is threaded to this dimension, the toe setting will be close to the original (Courtesy of Dana Corporation) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 90–38 All tie rod ends should be installed so that the stud is in the center of its operating range, as shown Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: To ensure proper wheel alignment, install the adjusting sleeve  with an equal number of threads showing at each end of the sleeve. Some  manufacturers also specify a minimum of three threads showing at each  end. If the sleeve itself is corroded or bent, it should be replaced along with  either or both of the tie rod ends (inner and outer).  Figure 90–39 (a) Tie rod adjusting sleeve (b) Be sure to position the clamp correctly on the sleeve Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Service of Ball Socket Assemblies  Inner tie rod end  assemblies used on rack­and­pinion steering units require  special consideration and often special tools.  A test of this joint is performed by disconnecting the outer  tie rod end and  measuring the effort required to move the  tie rod in the socket. This is called the articulation test Figure 90–40 An articulation test uses a spring scale to measure the amount of force needed to move the tie rod in the ball socket assembly Most manufacturers specify a minimum of lb (4.4 N) of force and a maximum of lb (26 N) Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Removing a ball socket assembly usually requires the use of two  wrenches or a special tool.  Figure 90–41 Removing a staked inner tie rod assembly requires two wrenches—one to hold the rack and the other to unscrew the joint from the end of the steering rack Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The flange around the outer tie rod must be restaked to the flat  shoulder on the end of the rack, as shown here Figure 90–42 When the inner tie rod end is reassembled, both sides of the housing must be staked down onto the flat shoulder of the rack Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Always follow the instructions that come with replacement part(s).  Figure 90–43 After replacing an inner tie rod end, the socket assembly should be secured with a rivet or set screw depending on the style of the replacement part Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: When replacing a rack­and­pinion assembly, specify a long rack rather than a short rack. A short rack does not include the bellows (boots) or inner tie rod ends (ball socket assemblies). The labor and cost required to exchange or replace these parts usually make it easier and less expensive  to replace the entire steering unit Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Dry Part Test Step-By-Step Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Dry Part Test Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY The dry park test is a very important test to detect worn or  damaged steering parts. With the vehicle on the ground, have an assistant move the steering wheel back and forth while the  technician feels for any looseness in each steering system part The steering system must be level side­to­side to prevent  unwanted bump steer. Bump steer is when the vehicle’s direction  is changed when traveling over bumps or dips in the road The idler arm usually is the first steering system component to  wear out in a conventional parallelogram­type steering system.  Following the idler arm in wear are the tie rods, center link, and  then the pitman arm Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 ... Voltage ranges from 0.25 volts? ?at? ?approximately one full turn left  to 4.75 volts? ?at? ?approximately one full turn right. The voltage will  then  remain? ?at? ?that level for the remainder? ?of? ?steering wheel travel.  Continued Automotive. .. employee of the Alemite Corporation, a manufacturer of pressure lubrication equipment A zerk or grease fitting is also known as an Alemite fitting It is important that all? ?of? ?these joints be lubricated with chassis ... The proper operation of the steering system is critical to the safe operation of any vehicle Always follow the service procedures specified by the vehicle manufacturer Automotive Technology: Principles,

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  • PowerPoint Presentation

  • OBJECTIVES:

  • Slide 3

  • KEY TERMS:

  • Slide 5

  • STEERING LINKAGE

  • Figure 90–1 Steering movement is transferred from the pitman arm that is splined to the sector shaft (pitman shaft), through the center link and tie rods, to the steeting knuckle at each front wheel. The idler arm supports the passenger side of the center link and keeps the steering linkage level with the road. (Courtesy of Dana Corporation)

  • Slide 8

  • Figure 90–2 The most common type of steering is the parallelogram. The cross-steer and Haltenberger linkage designs are used on some trucks and vans.

  • Slide 10

  • Slide 11

  • Slide 12

  • Figure 90–4 (a) A dual bearing design with a preload spring. The use of two bearing surfaces allows for one surfaces for rotation (for steering) and another surface for pivoting (to allow for suspension up-and-down movement). (b) The nylon wedge bearing type allows for extended lube intervals. Wear is automatically compensated for by the tapered design and spring-loaded bearing.

  • Figure 90–5 (a) A rubber-bonded socket is constructed of a rubber casing surrounding the ball stud, which is then inserted into the socket of the tie rod end. The hole in the socket allows air to escape as the ball stud is installed and there is not a place for a grease fitting. (b) The socket is crimped over the ball so that part of the socket lip retains the stud.

  • RACK-AND-PINION INNER TIE ROD ENDS

  • Figure 90–7 A variety of methods are used to secure the inner tie rod end socket assembly to the end of the rack.

  • Figure 90–8 Exploded view of a center-take-off-style rack-and-pinion steering gear assembly.

  • Slide 18

  • Figure 90–9 In a rear-steer vehicle, the steering linkage is behind the centerline of the front wheels, whereas the linkage is in front on a front-steer vehicle.

  • FOUR-WHEEL STEERING

  • Figure 90–10 Opposite-phase four-wheel steer is usually used only at low vehicle speed to help in parking maneuvers. Sample-phase steering helps at higher speeds and may not be noticeable by the average driver.

  • Figure 90–11 Being equipped with four-wheel steer allows a truck to make shorter turns than would otherwise be possible.

  • Slide 23

  • Figure 90–12 The Quadrasteer system includes many components that all work together.

  • Figure 90–13 Rear steer select switch schematic.

  • Slide 26

  • Slide 27

  • Slide 28

  • Slide 29

  • Figure 90–14 The dash-mounted select switch showing the three positions for the four-wheel steer system.

  • Slide 31

  • Slide 32

  • Figure 90–15 The output of the handwheel sensor digital signal.

  • Slide 34

  • Figure 90–16 Handwheel analog signal.

  • Slide 36

  • Figure 90–17 Handwheel position sensor analog signal to control module.

  • Figure 90–18 Handwheel position sensor digital signal to control module.

  • Slide 39

  • Slide 40

  • Figure 90–19 A Quadrasteer system showing all of the components. The motor used to power the rear steering rack can draw close to 60 amperes during a hard turn and can be monitored using a Tech 2.

  • STEERING LINKAGE LUBRICATION

  • Figure 90–21 Part of steering linkage lubrication is applying grease to the steering stops. If these stops are not lubricated, a grinding sound may be heard when the vehicle hits a bump when the wheels are turned all the way one direction or the other. This often occurs when driving into or out of a driveway that has a curb.

  • Slide 44

  • Slide 45

  • DRY PARK TEST

  • Slide 47

  • Figure 90–22 Checking for freeplay in the steering.

  • Figure 90–23 All joints should be felt during a dry park test. Even inner tie rod ends (ball socket assemblies) can be felt through the rubber bellows on many rack-and-pinion steering units.

  • Slide 50

  • Slide 51

  • COMMON WEAR TERMS

  • Slide 53

  • Slide 54

  • Slide 55

  • Slide 56

  • UNDER-VEHICLE INSPECTION

  • Slide 58

  • Figure 90–29 Steering system component(s) should be replaced if any noticeable looseness is detected when moved by hand.

  • Figure 90–30 All joints should be checked by hand for any lateral or vertical play.

  • Slide 61

  • Slide 62

  • Slide 63

  • Slide 64

  • STEERING LINKAGE REPLACEMENT

  • Figure 90–32 The preferred method for separating the tie rod end from the steering knuckle is to use a puller such as the one shown. A pickle-fork-type tool should only be used if the tie rod end is going to be replaced. A pickle-fork-type tool can damage or tear the rubber grease boot.

  • Figure 90–33 Two hammers being used to disconnect a tie rod end from the steering knuckle. One hammer is used as a backing for the second hammer. Notice that the attaching nut has been loosened, but not removed. This prevents the tie rod end from falling when the tapered connection is knocked loose.

  • Figure 90–34 A pitman arm puller is used to remove the pitman arm from the pitman shaft.

  • Slide 69

  • Slide 70

  • Slide 71

  • Figure 90–37 Replacement tie rods should be of the same overall length as the originals. Measure from the edge of the tie rod sleeve to the center of the grease fitting. When the new tie rod is threaded to this dimension, the toe setting will be close to the original. (Courtesy of Dana Corporation)

  • Figure 90–38 All tie rod ends should be installed so that the stud is in the center of its operating range, as shown.

  • Slide 74

  • Figure 90–40 An articulation test uses a spring scale to measure the amount of force needed to move the tie rod in the ball socket assembly. Most manufacturers specify a minimum of 1 lb (4.4 N) of force and a maximum of 6 lb (26 N).

  • Figure 90–41 Removing a staked inner tie rod assembly requires two wrenches—one to hold the rack and the other to unscrew the joint from the end of the steering rack.

  • Figure 90–42 When the inner tie rod end is reassembled, both sides of the housing must be staked down onto the flat shoulder of the rack.

  • Figure 90–43 After replacing an inner tie rod end, the socket assembly should be secured with a rivet or set screw depending on the style of the replacement part.

  • Slide 79

  • Slide 80

  • Slide 81

  • SUMMARY

  • Slide 83

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