The role of the steering gear is to appropriately convert the steering torque and steering angle from the steering wheel (mainly decelerating and increasing torque), and then output it to the steering rod mechanism to steer the car, so the steering gear is essentially a reduction gear transmission. There are many types of steering gear, such as rack and pinion, recirculating ball type, worm crank pin type, power steering gear and so on.
According to the classification of power assistance, steering gear can be divided into mechanical (non-assisted) and powered (assisted). Mechanical steering gear can be divided into rack and pinion type, recirculating ball type, worm crank pin type, recirculating ball crank pin type, worm roller type and so on according to different structural forms. Commonly used are rack and pinion, recirculating ball, and worm crank finger pins.
The rack and pinion steering gear is the simplest steering gear. It has the advantages of simple structure, compactness, high rigidity, low cost, sensitive steering, high forward and reverse attack rates, easy to arrange, and is particularly suitable for use with candle-type and Macpherson suspensions. It can also be directly used. Drive the tie rod to simplify the steering transmission. Therefore, it is widely used in cars and mini and light trucks.
The recirculating ball steering gear has a high forward and reverse attack rate, so it is easy to handle, has a long life, and is stable and reliable. However, due to the high reverse attack rate, it is easy to transmit the road impact to the steering wheel.
Power steering is actually a combination of mechanical steering and steering booster. Depending on the energy transfer medium, the power steering gear has two types: pneumatic and hydraulic. Among them, the hydraulic power steering gear can be divided into integral types (mechanical steering gear, steering power cylinder, and steering power cylinder and steering power cylinder) according to the different arrangements and connection relationships of the three in the steering gear. The three steering control valves are designed as a whole), semi-integrated (the mechanical steering gear and the steering control valve are designed together, and the steering power cylinder is independent) and the separate type (the mechanical steering gear is independent, the steering control valve and the steering power cylinder are integrated) Design as one) three structural types. It is worth noting that pneumatically powered steering gears are not suitable for trucks with very large loading masses, because the working pressure of the pneumatic system is relatively low (generally no higher than 0.7 MPa), and its size will be too large when used on heavy-duty vehicles. The working pressure of hydraulic power steering gear can reach more than 10MPa, so its component size is very small. The hydraulic system works without noise, has a short working lag time, and can absorb shocks from uneven roads. Therefore, hydraulic power steering has been widely used in various types of automobiles.