Design and verification of steering GAZelle Next

The vehicle's steering system is equipped with hydraulic power steering and a rack and pinion steering mechanism.

The steering linkage consists of two tie rods, connected via ball joints to the steering knuckle arms.

The steering mechanism is mounted on the crossmember of the front suspension.

The pressure of the working fluid in the power steering system is maintained by a vane pump, which is driven by a belt from the engine crankshaft pulley.

Power steering pump — **Fig. 2.** Hydraulic power steering pump.

Fluid is supplied to the pump and then, under high pressure, directed to the rotary valve mechanism, which is installed on the steering gear housing and rigidly connected to the steering column.

Steering mechanism assembly — **Fig. 3.** Steering mechanism: 1 – pinion shaft; 2 – rotary valve mechanism; 3 – fluid supply lines; 4, 11 – tie rods; 5, 13 – ball joints of the outer tie rod ends; 6, 12 – outer tie rod ends; 7, 10 – tie rod protective boots; 8 – steering gear housing integrated with the hydraulic cylinder; 9 – threaded rack stop.

When the steering wheel is turned, the valve mechanism connects one of the hydraulic cylinder cavities (integrated into the steering gear housing) to the high-pressure line, and the other to the fluid return line to the reservoir.

The rack, connected to the hydraulic cylinder piston, moves within the steering gear housing under the action of the pinion and the pressure difference in the cylinder cavities.

As it moves, the rack transmits force to the steering knuckles via the tie rods, causing the front steered wheels of the vehicle to turn.

Important: In the event of power steering failure, the vehicle remains steerable, but the effort required to turn the steering wheel increases significantly.

Steering column construction — **Fig. 4.** Steering column: 1 – ball joint of the intermediate shaft; 2 – upper intermediate shaft; 3 – universal joint of the intermediate shaft; 4 – steering shaft; 5 – steering column; 6 – mounting bracket; 7 – tilt adjustment mechanism; 8 – splined end of the steering shaft.

The vehicle is fitted with an energy-absorbing (safe) steering column equipped with a tilt adjustment mechanism.

The upper intermediate shaft is connected to the main steering shaft via a universal joint.

The lower end of the upper intermediate shaft is secured to the cab floor via a ball joint.

Clamp connection of the yoke — **Fig. 5.** Clamp connection of the universal joint yoke.

The yoke «Б» of the universal joint of the lower intermediate shaft «А» is attached to the lower end of the upper intermediate shaft via a clamp connection.

The lower intermediate shaft «А» is similarly attached to the tail «Б» of the steering gear pinion shaft via a clamp connection.

Safety note: This design prevents the steering column from intruding into the cabin in the event of frame deformation during a frontal collision, minimising the risk of the driver being injured by impact with the steering wheel.

For additional protection, the steering shaft is made in two parts, joined together by a splined telescopic connection.

Mounted on the steering column are: the ignition switch with a steering lock anti-theft device, and the stalk switch assembly (controlling headlights, indicators, windscreen washer, and wipers).

The power steering reservoir is mounted on a bracket at the front of the engine bay, on the upper crossmember of the radiator frame. It is connected via hoses to the power steering pump and the fluid return line.

Reservoir dipstick — **Fig. 8.** Fluid level indicator (dipstick) integrated into the reservoir cap.

To monitor the fluid level, a dipstick is mounted on the reservoir cap, marked with minimum and maximum level indicators.

The tie rods are attached to the steering gear rack and to the front suspension steering knuckles via ball joints.

To prevent spontaneous rotation within the ends, the tie rods are secured with locknuts.

Rotating the adjustment sleeve of the tie rod within the end allows for the adjustment of the steered wheels' toe-in.

Possible steering system faults and remedies

1. Excessive steering wheel free play (lash) and knocking in the steering:

— Loose steering gear mounting bolts and nuts — Tighten bolts and nuts to the specified torque.
— Wear of the tie rod ball joints — Replace the outer tie rod ends or complete tie rod assemblies.
— Wear of the intermediate shaft universal joints — Replace the complete intermediate shaft assembly.

2. Difficult steering wheel rotation (insufficient assistance):

— Slipping or damage to the pump drive belt — Replace the belt.
— Low working fluid level — Top up the fluid to the normal level.
— Air in the hydraulic system — Bleed the system to remove air.
— Twisting or damage to high/low-pressure hoses — Remove twisting or replace the hoses.
— Insufficient pump pressure or excessive internal leakage — Replace the power steering pump.
— Fluid leaks from the steering gear — Replace defective sealing elements or the complete steering gear.

3. Poor return of the steering wheel to the centre position:

— Difficult rotation of the tie rod end ball joints — Replace the tie rod ends or complete tie rod assemblies.
— Rack deformation or pinion bearing damage — Replace the steering gear.
— Twisting of power steering hoses — Remove twisting or replace the hoses.
— Damage to the pressure control valve or pump rotor shaft bearing — Replace the relevant component.
— Incorrect rack stop adjustment (too tight) — Adjust the rack stop clearance.

4. Noise (knocking) in the steering:

— Loose steering gear or ball joint mounting — Tighten the threaded connections.
— Wear of the ball joints — Replace worn components.
— Incorrect rack stop adjustment (too loose) — Adjust the rack stop.

5. Excessive noise from the power steering pump:

— Low fluid level or air in the system — Restore the fluid level and bleed the air from the system.
— Loose pump mounting bolts — Tighten the mounting bolts.

Important (materials used): The power steering system must be filled with Automatic Transmission Fluid (ATF) meeting the Dexron III specification or higher. Recommended products: Shell Spirax S2 ATF AX, Mobil ATF+4, Castrol Transmax Dex/Merc, Esso.

Steering system inspection

Steering wheel spoke position — **Fig. 9.** Checking the position of the steering wheel spokes.

Check the position of the steering wheel spokes: when the front wheels are in the straight-ahead position, they should be symmetrical relative to the vertical axis. If not, identify the cause of the fault (e.g., incorrect toe adjustment) and rectify it.

Tie rod end protective boots — **Fig. 10.** Checking the condition of the protective boots on the tie rod ends.

Check the condition of the protective boots on the tie rod ends. Torn, cracked, or hardened rubber boots must be replaced immediately. Otherwise, water, dust, and dirt entering the joints will quickly cause them to fail.

By sharply turning the steering wheel in both directions (this operation should be performed by an assistant), visually and audibly check the mounting of the steering gear. Movement of the mechanism or knocking is not permitted.

If you detect knocking or binding that prevents the steering wheel from turning, disconnect the tie rods from the steering knuckle arms and repeat the check. If the knocking or binding persists, remove the steering gear from the vehicle for diagnosis and repair.

Play in ball joints — **Fig. 11.** Checking for play in the tie rod end ball joints.

Check for play in the ball joints of the tie rod ends. Tie rod ends with perceptible play in their joints must be replaced.

Also check the tightness of the ball joint stud nuts.

Check the condition of the tie rod protective boots. Replace any damaged boots immediately.

Check the condition of the intermediate shaft universal joints for wear and play.

Check the condition and secure mounting of the upper intermediate shaft ball joint.

Fluid level in reservoir — **Fig. 15.** Checking the level and cleanliness of the working fluid in the reservoir.

Check the level and cleanliness of the working fluid in the reservoir. Also check the condition of the hoses and pipes connecting the power steering system components. Rectify any leaks found.

Checking steering wheel play

Required tools: a ruler, chalk or a marker for making marks.

Excessive steering wheel free play makes vehicle control difficult, as the vehicle reacts sluggishly to driver inputs. Furthermore, excessive play that cannot be eliminated by adjustment indicates a steering system fault (loose mounting of the gear or tie rods, or wear of their components).

Check the steering wheel play with the vehicle parked on a flat, dry, and non-slip surface.

The play must not exceed 5°. For a steering wheel with an outer diameter of 360 mm, the linear play must not exceed 15–17 mm.

Set the front wheels to the straight-ahead position.

Ruler placement — **Fig. 16.** Placing the ruler to check for play.

Place the ruler so that its end rests against the dashboard and its flat surface touches the outer surface of the steering wheel rim.

Turning wheel right — **Fig. 17.** Turning the steering wheel to the right until the wheels begin to turn.

Without changing the position of the ruler, turn the steering wheel to the right until the front wheels just begin to turn. In this position, make a mark on the steering wheel rim.

Turning wheel left — **Fig. 18.** Turning the steering wheel to the left until the wheels begin to turn.

Without changing the position of the ruler, turn the steering wheel to the left until the front wheels just begin to turn. In this position, make a second mark on the steering wheel rim.

Measuring distance — **Fig. 19.** Measuring the distance between the marks.

Measure the distance between the marks along the rim. It must not exceed the calculated maximum limit. If the distance (steering wheel free play) is greater than the norm, the cause of the fault must be identified and rectified.