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Steering ColumnsSteering Columns

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Steering column componentsSteering column components

• Steering wheel• Air bag• Clock Spring• Steering lock plate• Steering angle

sensor• Cancel cam • Lock cylinder• Ignition switch• Turn signal switch

• Steering wheel• Air bag• Clock Spring• Steering lock plate• Steering angle

sensor• Cancel cam • Lock cylinder• Ignition switch• Turn signal switch

• Headlight switch• Wiper washer

switch• Cruise control

switch• Upper steering

shaft• Lower steering

shaft• Shaft bearings [3]• Tilt housing• Constant velocity

joint• Steering coupler

• Headlight switch• Wiper washer

switch• Cruise control

switch• Upper steering

shaft• Lower steering

shaft• Shaft bearings [3]• Tilt housing• Constant velocity

joint• Steering coupler

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Steering columns and crash survivabilitySteering columns and crash survivability

• The modern steering column is the result of thousands of crash tests.

• The information learned from each test has helped thousands of people survive accidents that would have been fatal in older vehicles.

• In a crash the steering has to be capable of collapsing from both ends.

• This prevents the steering column and shaft impaling the driver’s chest and helps to absorb the kinetic energy of the drivers body.

• The modern steering column is the result of thousands of crash tests.

• The information learned from each test has helped thousands of people survive accidents that would have been fatal in older vehicles.

• In a crash the steering has to be capable of collapsing from both ends.

• This prevents the steering column and shaft impaling the driver’s chest and helps to absorb the kinetic energy of the drivers body.

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Steering shafts and couplingsSteering shafts and couplings

• The connection between the steering wheel and pinion shaft/worm shaft is normally in three parts.

• The connection between the steering wheel and pinion shaft/worm shaft is normally in three parts.

• Upper steering shaft• Intermediate steering

shaft• Steering coupler

• Upper steering shaft• Intermediate steering

shaft• Steering coupler

Upper steering

shaft

Intermediate shaft

Steering coupler

Pinion shaft

Spline for steering wheel

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Steering wheelSteering wheel• The steering wheel is connected

to the upper steering shaft via a tapered spline.

• Once the steering wheel retaining nut has been torqued the steering wheel can only be removed from the steering shaft by a steering wheel puller.

• Two threaded holes on either side of the spline are provided for the puller tool.

• The steering wheel is connected to the upper steering shaft via a tapered spline.

• Once the steering wheel retaining nut has been torqued the steering wheel can only be removed from the steering shaft by a steering wheel puller.

• Two threaded holes on either side of the spline are provided for the puller tool.

• A pass through hole in the hub allows the electrical connector for the air bag, horn switch and steering wheel mounted switches to connect to the clock spring.

• A pass through hole in the hub allows the electrical connector for the air bag, horn switch and steering wheel mounted switches to connect to the clock spring.

Steering shaft spline

8mm x 1.25 tapped holes

Index marks

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Steering shaft constant velocity jointSteering shaft constant velocity joint

• Nearly all modern cars have tilt wheel type steering columns.

• A constant velocity type joint is needed to allow the steering effort to pass through a 0o to 20o angle without the steering being jerky.

• The constant velocity joint connects the upper shaft to the intermediate shaft.

• Nearly all modern cars have tilt wheel type steering columns.

• A constant velocity type joint is needed to allow the steering effort to pass through a 0o to 20o angle without the steering being jerky.

• The constant velocity joint connects the upper shaft to the intermediate shaft.

Upper steering shaft

Intermediate shaftConstant

velocity joint

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Intermediate shaftIntermediate shaft

• The intermediate shaft is collapsible.• The outer shaft is hollow allowing the solid

inner shaft to telescope into the outer shaft tube.

• Whenever working on a steering column you must be careful to not tap on the ends of the shafts or exert any pressure that might shorten the assembly.

• The intermediate shaft is collapsible.• The outer shaft is hollow allowing the solid

inner shaft to telescope into the outer shaft tube.

• Whenever working on a steering column you must be careful to not tap on the ends of the shafts or exert any pressure that might shorten the assembly.

Upper steering shaft

Outer shaft

Inner shaft

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Shaft support bearingsShaft support bearings

• The intermediate shaft and the upper shaft are supported by sealed ball bearings.

• The intermediate shaft and the upper shaft are supported by sealed ball bearings.

Sealed ball bearings

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Steering CouplerSteering Coupler

• The coupler connects the intermediate shaft to the pinion shaft or worm shaft.

• Like the intermediate shaft the coupler also telescopes.

• This allows the sub-frame and rack to move on their rubber mounts without passing shock and vibration into the intermediate shaft.

• The coupler connects the intermediate shaft to the pinion shaft or worm shaft.

• Like the intermediate shaft the coupler also telescopes.

• This allows the sub-frame and rack to move on their rubber mounts without passing shock and vibration into the intermediate shaft.

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Steering CouplerSteering Coupler

• The coupler is mounted at an angle relative to the steering column so that in a severe frontal impact the sub-frame and rack will be pushed downward and under the firewall.

• The coupler is mounted at an angle relative to the steering column so that in a severe frontal impact the sub-frame and rack will be pushed downward and under the firewall.

• The steering coupler is normally located on the engine compartment side of the firewall.

• The steering coupler is normally located on the engine compartment side of the firewall.

Frontal impact forces coupler

downward

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Pinch bolt jointsPinch bolt joints

• Steering couplers are normally attached to shafts via a pinch bolt joint.

• The joint and shaft are connected by ‘D’ shaped splines.

• The pinch bolt passes through the notch in the shaft as a safety mechanism – if the bolt loosens the joint will not separate from the shaft.

• Steering couplers are normally attached to shafts via a pinch bolt joint.

• The joint and shaft are connected by ‘D’ shaped splines.

• The pinch bolt passes through the notch in the shaft as a safety mechanism – if the bolt loosens the joint will not separate from the shaft.

‘D’ shaped spline

Center of joint is ‘D’ shaped to match spline on shaft

Notch in shaft

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Outer columnOuter column

• The housing connects to brackets on the body that can breakaway and slide inward in a crash

• The housing connects to brackets on the body that can breakaway and slide inward in a crash

• The shafts and bearings are supported by a collapsible steel housing.

• The shafts and bearings are supported by a collapsible steel housing.

Breakaway bracket

Firewall

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Outer columnOuter column• A rubber grommet

mounted in the firewall prevents dirt and water from entering the passenger compartment

Grommet

Plastic boot

• A plastic boot located between the steering rack and firewall helps to keep dirt and water away from the grommet.

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Upper columnUpper column

• The clock spring connects the air bag, horn and electrical switches mounted on the steering wheel cover to the vehicles electrical system.

• It is mounted to the tilt assembly directly below the steering wheel.

• The clock spring connects the air bag, horn and electrical switches mounted on the steering wheel cover to the vehicles electrical system.

• It is mounted to the tilt assembly directly below the steering wheel.

Clock spring

Combination Switch[s]

Upper column tilt bearing

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Clock SpringClock Spring

• The clock spring is a spool of ribbon cable that winds and unwinds as the steering wheel is turned.

• Most clock springs can turn about 4 to 5 turns from fully unwound to fully wound.

• The clock spring is a spool of ribbon cable that winds and unwinds as the steering wheel is turned.

• Most clock springs can turn about 4 to 5 turns from fully unwound to fully wound.

• To prevent damage to the clock spring it must be centered and removed whenever the steering gear is serviced.

• To center the clock spring turn the wheels to straight ahead with the steering wheel at 12 o’clock.

• To prevent damage to the clock spring it must be centered and removed whenever the steering gear is serviced.

• To center the clock spring turn the wheels to straight ahead with the steering wheel at 12 o’clock.

Inner sleeve keyed to

steering wheelIndex marks

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Upper columnUpper column

• The combination switch assembly is mounted to the outer face of the tilting assembly.

• The combination switch is operated by the stalks on the outside of the steering column.

• Some manufactures integrated all the switches into one assembly.

• Otherwise there are two switches on either side.

• The combination switch assembly is mounted to the outer face of the tilting assembly.

• The combination switch is operated by the stalks on the outside of the steering column.

• Some manufactures integrated all the switches into one assembly.

• Otherwise there are two switches on either side.

Clock spring

Combination Switch[s]

Upper column tilt bearing

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Upper columnUpper column

• The tilt mechanism is spring loaded so that the steering wheel will rise if the lock lever is released by accident.

• The lock lever clamps the sides of the tilt assembly to the housing.

• The tilt mechanism is spring loaded so that the steering wheel will rise if the lock lever is released by accident.

• The lock lever clamps the sides of the tilt assembly to the housing.

Upper column tilt bearing

Upper column tilt bearing

Tilt up springTilt up spring

Tilt assemblyTilt assembly

HousingHousing

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Plate type steering lockPlate type steering lock

• The steering lock plate is a stamped steel plate that is splined to the steering shaft.

• When the ignition key is turned to the lock position the actuating rod pushes a spring loaded locking pint into a notch in the lock plate.

• The steering lock plate is a stamped steel plate that is splined to the steering shaft.

• When the ignition key is turned to the lock position the actuating rod pushes a spring loaded locking pint into a notch in the lock plate.

Lock plate

Lock plate splined to steering shaft

Lock cylinder

Actuating rod

Spring loaded

locking pin

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Pawl type steering lockPawl type steering lock

• In this type of lock mechanism a pawl gear is machined directly on the intermediate steering shaft.

• The locking pin is actuated directly off of a cam on the back of the lock cylinder.

• In this type of lock mechanism a pawl gear is machined directly on the intermediate steering shaft.

• The locking pin is actuated directly off of a cam on the back of the lock cylinder.

Lock cylinder

Cam

Pawl gear

Steering shaft

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Steering locks for keyless ignition Steering locks for keyless ignition

• Keyless ignition systems use a radio transmitter to actuate the door locks and ignition system and do not have a conventional lock cylinder on the steering column.

• To lock the steering system a small electric motor moves the locking pin into and out of the pawl gear when commanded by the BCM or security system control module.

• Keyless ignition systems use a radio transmitter to actuate the door locks and ignition system and do not have a conventional lock cylinder on the steering column.

• To lock the steering system a small electric motor moves the locking pin into and out of the pawl gear when commanded by the BCM or security system control module.

Electric motor

Worm gear

Spring loaded lock pin

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Lock cylinderLock cylinder

• Mechanical lock cylinders are mounted to the lower section [stationary] of the steering column housing.

• The lock cylinder is retained in its bore in the housing by a spring loaded pin.

• Inserting a pin punch into a small hole in the housing will depress the lock pin so that the entire lock cylinder can be removed.

• The lock cylinder must be in the accessory position to allow the pin to be depressed.

• Mechanical lock cylinders are mounted to the lower section [stationary] of the steering column housing.

• The lock cylinder is retained in its bore in the housing by a spring loaded pin.

• Inserting a pin punch into a small hole in the housing will depress the lock pin so that the entire lock cylinder can be removed.

• The lock cylinder must be in the accessory position to allow the pin to be depressed.

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Ignition switchIgnition switch

• Ignition switches are actuated directly by the lock cylinder or remotely by an actuating rod.

• Most modern cars have a direct acting ignition switch bolted the lock cylinder housing.

• Remote ignition switches are located on the base of the steering column housing and are actuated by a rod that connects to the lock cylinder at the top of the column.

• Remote ignition switches have slotted screw holes that allow the switch to be adjusted.

• Ignition switches are actuated directly by the lock cylinder or remotely by an actuating rod.

• Most modern cars have a direct acting ignition switch bolted the lock cylinder housing.

• Remote ignition switches are located on the base of the steering column housing and are actuated by a rod that connects to the lock cylinder at the top of the column.

• Remote ignition switches have slotted screw holes that allow the switch to be adjusted.

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Turn signal cancel camTurn signal cancel cam

• The cancel cam triggers the turn signal switch to turn off after the turn has been completed.

• If the cancel cam is not positioned properly on the steering shaft the turn signals will not cancel correctly.

• The cancel cam triggers the turn signal switch to turn off after the turn has been completed.

• If the cancel cam is not positioned properly on the steering shaft the turn signals will not cancel correctly.

Combination switch assembly

Cancel cam splined to

steering shaft

Cancel pin on turn signal switch