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1、Welcome To,Steering System Operation & Diagnosis,SECTION 17,Objectives,Describe the similarities and differences between parallelogram, worm and roller, and rack-and-pinion steering linkage systems. Identify the typical manual steering system components and their functions. Name the five basic types
2、 of steering linkage systems.,continued,Objectives,Identify the components in a parallelogram steering linkage arrangement and describe the function of each. Identify the components in a manual rack-and-pinion steering arrangement and describe the function of each.,continued,Objectives,Describe the
3、function and operation of a manual steering gearbox and the steering column. Explain the various manual steering service procedures. Describe the service to the various power steering designs.,continued,Objectives,Perform general power steering system checks. Describe the common four-wheel steering
4、systems.,continued,Parallelogram Steering Components,Pitman arm Connects the linkage to the steering gear. Idler arm Supports the centre link to the frame. Centre link, drag link, or steering link Controls sideways linkage movement. Tie-rods Connect linkage to the steering knuckles.,continued,Parall
5、elogram Steering,continued,Tilt and telescopic steering,Steering column assembly,A recirculation-ball system,Recirculating-ball system using a parallelogram linkage,A typical rack-and-pinion steering system,A typical hydraulic power-assisted system,Rack-and-Pinion Steering,Rack Is a toothed bar in a
6、 metal housing that acts similarly to a centre link. Pinion Is a worm gear attached to the steering column that transfers movement to the rack. Tie-rods Connect the rack to the steering knuckles.,continued,A Rack-and-Pinion Steering System,continued,Power Steering System Types,continued,Power Steeri
7、ng Pump Types,Roller Slipper Gear Vane (the most common) The vane, roller, and slipper pumps are similar in construction and are all positive displacement balanced pumps. The vane pump consists of a slotted centre rotor, a number of flat vanes that are fitted into the slotted rotor, and an outer pum
8、p cam or cam ring that is slightly elliptical in shape to form 2 pumping chambers.,continued,Vane Type Power Steering Pump,continued,Power Steering Components,Fluid Pump Fluid reservoir Flow control valve Pressure relief valve Hoses Gearbox or rack,continued,Electronic Power Steering Systems,Pressur
9、e control valve (PCV) type Uses a current-controlled valve to vary power steering system pressure. Variable effort steering (VES) type Uses a pulse width modulated valve to vary power steering system pressure. Magna-steer type Uses a spool valve and electromagnetic device to control the amount of as
10、sist.,continued,Variable Effort (Electronically Controlled) Power Steering,continued,Electric/Electronic Rack & Pinion,continued,Common Steering System Complaints,Excessive play Feedback Hard steering Nibble or slight shimmy,Pulling or drifting Shimmy Poor return Wandering,continued,Tire Wear Patter
11、ns,continued,Power Steering Leak Points,continued,Power Steering Leak Points,continued,Steering Components to be checked during diagnosis,continued,Four-Wheel Steering (4WS),Most cars tend to understeer or, in a few instances, oversteer. If a car could automatically compensate for an understeer/over
12、steer problem, a nearly neutral steering under varying operating conditions. Four-wheel steering is a serious effort on the part of automotive design engineers to provide near-neutral steering.,continued,Four-Wheel Steering (4WS),The various types of four-wheel steering systems; Mechanical 4WS Hydra
13、ulic 4WS Electro/Hydraulic 4WS Quadrasteer,continued,A Comparison of 2WS and 4WS,continued,A Hydraulic 4WS System,continued,An Electro/Hydraulic 4WS System,continued,Air Bag Safety Precautions,Always wear safety glasses. Follow the manufacturers procedure for disarming the system before servicing. N
14、ever probe the connectors on the air bag module. Always carry an air bag module with the trim facing away from your body.,continued,Air Bag Safety Precautions,Never set a live air bag module down with the trim cover facing down. Wash your hands with soap and water after working around a deployed air
15、 bag.,continued,Summary,The components of a manual steering system include the steering linkage, steering gear, and the steering column and wheel. Basic components of a parallelogram steering linkage system include the pitman arm, idler arm, links, tie-rods, and in some designs, a steering damper.,c
16、ontinued,Summary,In rack-and-pinion steering linkage, steering input is received from a pinion gear attached to the steering column. There are three types of manual steering gears in use today: recirculating ball, worm and roller, and rack-and-pinion.,continued,Summary,The major components of a conventional power steering system are the steering linkage, power-steering pump, valves, reservoir, hoses, and gearbox. There are several variations of electronically
