11-134610-00
1. OVERVIEW
The power steering has been designed to make the wheel move more easily than in a manual steering
system. The hydraulic power assists the process utilizing hydraulic fluid. The fluid increases pressure
in the power steering pump and aids the movement of the steering mechanism. The power steering
system consists of pump, oil reservoir, rack and gear box. The power steering pump is a vane type
and delivers hydraulic pressure to operate the power steering system. The pressure relief valve in the
pump controls the discharging pressure. The rotary valve in the rack and the pinion gear directs the oil
from the power steering pump to one side of the rack piston. The integrated rack piston converts the
hydraulic pressure to linear movement. The operating force of the rack moves the wheels through the
tie rod, the tie rod end and the steering knuckle. Even though the hydraulic pressure cannot be
generated, a driver can steer the vehicle without power assist but it needs very high steering force. In
this case, the operating force of the steering wheel is conveyed to the pinion, and the movement of the
pinion moves the rack through the pinion gear combined to the rack gear.
12-54170-01
1. OVERVIEW
A radial tire uses a cord angle of 90 degrees. That is, the cord material runs in a radial or direct line
from one bead to the other across the tread. In addition, a radial tire has a belt overwrap under the
tread surface to provide greater structural stability. The belt overwrap of a radial tire distortion while the
radial structure enables high speed driving.
Tire supports the weight of the vehicle, reduces the impact from the road and at the same time,
transmits the power to propel, brake and steer on the road. It also functions to maintain a
vehicle’s movement. In order to complete such tasks, a tire must be structured to be a resilient
vessel of air.
There is wear limit mark on the tire, which protrudes as a strip shape located approximately 1.6 mm
from the groove bottom. This wear limit mark is not seen from the outside so there is additional
"▲" mark on the shoulder to let the driver find the wear mark easily. To measure the tire groove
depth, measure at any point other than the point which has a wear limit mark.
The tire is worn unevenly according to the driver's driving habit, improper servicing, low tire inflation
pressure, changed tire location, etc.
1) Structure of Tire
Tread
This thick layer of rubber provides the interface
between the tire and the road. Wear-resistant
rubber is used to protect the carcass and belt
against fractures and impacts and to deliver a
long driving life.
Shoulder
Located between the tread and sidewall, the
shoulder rubber is the thickest so that the
design must allow for the easy diffusion of heat
generated within the tire while driving.
Sidewall
The part between the shoulder and bead, the
flexible sidewall protects the carcass and
enhances the ride. A tire’s type, size,
structure, pattern, manufacturing company,
product name and various characters are
indicated here. Bead
The bead attaches the tire to the rim and wraps
the end of the cord fabric. Comprised of the bead
wire, core, flipper and other parts, the bead is
generally designed to be slightly tight around the
rim so that in the case of a sudden drop in
inflation pressure, the tire will not fall off the rim.
Carcass
As the most important framework of a tire, the
entire inner layer of cord fabric is called the
carcass. The carcass acts to support air
pressure, vertical load and absorb shocks.
Valve
Belt
Bead core
