Land vehicles – Wheeled – Running gear
Reexamination Certificate
2000-09-25
2002-08-20
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Running gear
C280S093507
Reexamination Certificate
active
06435527
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a steering apparatus employed, for example, in industrial vehicles, more specifically to a steering apparatus provided with a toe-angle adjusting mechanism.
Generally, industrial vehicles, such as forklift trucks, are each provided with a steering apparatus for steering a pair of wheels in response to operation of a steering wheel. It is necessary to correctly set the direction of the wheels, or the relationship between the toe angle and the rotational position of the steering wheel, such that the vehicle travels along a straight line when the steering wheel is in the neutral position. However, discordance occurs in the relationship between the toe angle and the rotational position of the steering wheel due to errors in machining various parts of the steering apparatus and assembly errors, which may prevent the vehicles from running smoothly. Therefore, a step of correcting deviation of the toe angle is performed after wheels are attached to the rear axle.
Japanese Unexamined Patent Publication (KOKAI) No. Hei 10-76977 discloses a steering apparatus provided with a toe-angle adjusting mechanism. As shown in
FIG. 10
, the steering apparatus
71
is located in a rear axle
70
of a vehicle. A pair of steering knuckle arms
74
supporting a pair of rear wheels
76
are pivotally supported by kingpins
79
at the ends of the rear axle
70
, respectively. Each rear wheel
76
can be steered together with the steering knuckle arm
74
about the axis of the kingpin
79
.
The steering apparatus
71
includes a cylinder
73
having an operating rod
72
. The operating rod
72
has connecting pieces extended toward the rear wheels
76
, respectively. The pair of steering knuckle arms
74
are connected to the connecting pieces of the operating rod
72
through tie rods
75
, respectively. Each tie rod
75
and each steering knuckle arm
74
are connected pivotally relative to each other by a substantially cylindrical connecting shaft
77
. The connecting piece of the operating rod
72
and the tie rod
75
are connected pivotally relative to each other by an adjusting pin
78
. Axial movement of the operating rod
72
is converted by the tie rod
75
into pivotal movement of the corresponding steering knuckle arm
74
about the kingpin
79
.
As shown in
FIG. 11
, the adjusting pin
78
has a hexagonal head
78
d,
an upper supporting shaft portion
78
b,
an eccentric shaft portion
78
a
and a lower supporting shaft portion
78
c.
The axis of the eccentric shaft portion
78
a
(eccentric shaft axis X
2
) is offset by a predetermined distance, or the offset value T
1
, from the axis (main axis X
1
) of the upper and lower supporting shaft portions
78
b
and
78
c
and of the hexagonal head
78
d.
The adjusting pin
78
is fitted in an upper pin hole
72
a
and a lower pin hole
72
b
formed coaxially in the operating rod
72
. The eccentric shaft
78
a
is abutted only against the inner surface of a collar
80
, which is fitted in a pin hole
75
a
formed in the tie rod
75
. The hexagonal head
78
d
is fitted in a hexagonal hole defined in a locking plate
81
. The locking plate
81
is fixed to the operating rod
72
by a bolt
82
. The plate
81
prevents rotation of the adjusting pin
78
.
In adjusting the toe angle, the locking plate
81
is detached from the hexagonal head
78
d,
and the adjusting pin
78
is turned. The eccentric shaft axis X
2
moves along an imaginary circle, the radius of which is the offset value T
1
, drawn around the main axis X
1
. The distance between the main axis X
1
of the adjusting pin
78
and the axis of the connecting shaft
77
is changed depending on the position of the eccentric shaft axis X
2
, or the eccentric shaft
78
a.
The position of the knuckle arm
74
depends on this distance. The adjusting pin
78
is locked by fitting the locking plate
81
to the pin
78
after it is adjusted. This fixes the relationship between the wheel
76
and the rotational position of the steering wheel and adjusts the direction, or toe angle, of the rear wheel
76
.
In the conventional steering apparatus
71
, the locking plate
81
is abutted against a restricting face
72
c
formed on the operating rod
72
for immobilizing the locking plate
81
. This requires a step of forming the restricting face
72
c
on the operating rod
72
.
Variation in the accuracy of parts and errors in assembling them cause variation in the maximum steering angle of the rear wheel
76
. If the maximum steering angle is greater than a designed value, the rear wheel
76
can interfere with the body of the vehicle. However, the steering apparatus
71
does not account for errors in the maximum angle of the rear wheel.
Meanwhile, to form the eccentric shaft
78
a
having a great offset value T
1
on the adjusting pin
78
requires a relatively thick adjusting pin
78
and a great amount of machining, which leads to high material costs and much trouble and time.
SUMMARY OF THE INVENTION
A first objective of the present invention is to provide a mechanism for adjusting toe angle of wheels and a steering apparatus that facilitate machining and assembly of an operating rod and connecting pins. A second objective of the present invention is to provide a toe angle adjusting mechanism for a vehicle and a steering apparatus that can accurately adjust the toe angle of a wheel.
To achieve the above objective, the present invention provides a toe-angle adjusting mechanism for adjusting a toe angle of a wheel. The mechanism includes a steering knuckle arm pivotally supporting the wheel, an operating rod, which reciprocates in response to operation of a steering wheel, a tie rod connecting the operating rod with the steering knuckle arm to convert reciprocating movement of the operating rod into a pivotal movement of the steering knuckle arm, an adjusting pin pivotally connecting the operating rod with the tie rod, a connecting pin pivotally connecting the steering knuckle arm with the tie rod, and a locking element fitted against the pins. The adjusting pin includes an eccentric section and an engagement section. An outer surface of the eccentric section contacts either the operating rod or the tie rod. The distance between the operating rod and the steering knuckle arm changes depending on the rotational position of the adjusting pin. The locking element engages the engagement section and the connecting pin to prevent rotation of the adjusting pin.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 2371835 (1945-03-01), McNamara
patent: 3498630 (1970-03-01), Crawford
patent: 3982604 (1976-09-01), Crawford
patent: 4616845 (1986-10-01), Pettibone
patent: 5121808 (1992-06-01), Visentini et al.
patent: 5529316 (1996-06-01), Mattila
patent: 6007079 (1999-12-01), Kincaid et al.
patent: 6047789 (2000-04-01), Iwanaga
patent: 10-76977 (1998-03-01), None
Dunn David R.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
Swann J. J.
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