Note: Descriptions are shown in the official language in which they were submitted.
6~4
This invention relates to a steering column assembly
suitable for use in tilt-ca~ trucks.
In a tilt-cab truck, the steering box is fixed to
the chassis on which the ca~ is pivoted, while the steering
wheel is fixed in relation to the cab. A universal joint
is therefore provided between the steering wheel and the
steering box. Eowever, unless this joint lies on the cab
tilt axis, and such an arrangement can be difficult to real-
ize in practice, a further degree of relative movement is
necessary. Also, where the cab is resiliently mounted to
the truck frame, it is necessary to accommodate relative
movement of the steering wheel and steering box.
It has previously been proposed to use a two-part
telescopic steering column for these purposes. In such
known constructions, however, the two parts are provided with
accurately mating surfaces over a considerable length suf-
ficient to maintain accurate engagement over their entire
travel, This involves difficulty and expense in manufacture.
In accordance with one aspect of the present invention,
there is provided a steering column assembly comprising an
elongate upper column member for connection with a steering
wheel and an elongate lower column member for connection
with a steering box; the steering wheel being secured
directly to the upper column member; the lower column member
being telescopically received within the upper column member
for sliding movement between an operative and an inoperative
position; the upper column member having a first length of
its internal surface ad~acent the received end of the lower
column member, when in the operative position, dimensioned
to fit closely on the inner member and a second length
extending from its first length toward its receiving end
2 -
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diverging to provide a clearance; the portion of the lower
column member which lies, in the operative position, within
the first length of the upper column member being coated
with a low friction polytetrafluoroethylene material; the
upper and lower column members being of non-circular cross-
section; the upper column member comprises a tube and the
lower column member a rod; and bearing means supporting
the members for rotation about their longitudinal axis and
for limited tilting of the axis.
In accordance with another aspect of the present
invention, there is provided a steering column assembly
comprising an elongate upper column member Eor connection
with a steering wheel and an elonyate lower column member
for connection with a steering box; one of the column members
telescopically receiving the other of the column members
for sliding movement therein between an operative and an
inoperative position; the one column member having a first
length of its internal surface ad~acent the received end
of the other column member when in the operative position
dimensioned to fit closely on the other column member and
a second length extending from the first length towards its
receiving end diverging to provide a clearance; the one
column member is a tube and the other column member is a
rod; and bearing means supporting the members for rotation
about their longitudinal axis and for limited tilting of
the axis.
The invention is described further, by way of illus~
tration, with reference to the accompanying drawings, in
which:
Figure 1 is a side elevation, principally in cross-
section, of a steering arrangement embodying the invention
- 3 ~
in a tilt cab;
Figures 2 and 3 are cross-sections on the lines 2-2
and 3-3 respectively of Figure l; and
Figure 4 illustrates a step in the manufacture of
the embodiment.
Referring to the drawings, a steering box 10 is
secured to a chassis member 12 of a truck. A cab, the floor
of which is seen at 14, is mounted on the chassis to tilt
about a pivot axis 16. A steering wheel 18 is drivingly
connected by a steering column assembly to be described and
by a universal joint 20 to the steering box 40. Figure 1
shows these elements in the normal position of the cab.
The steering column assembly comprises an upper member
formed by a tube 22 of generally square cross-section, and
a lower member formed by a rod 24 of complementary section,
telescopically received within the tube 22. The tube 22
is secured at its upper end to the steering wheel 18; the
manner of securing these as seen in Figure 1 is described
in detail in U.S. Patent No. 4,166,400 assigned to Ford
Motor Company. ~ bracket 26 secured to the cab body provides
a part-spherical seat 28 in which is received a part~spher-
ical plastics body 30 which acts as a bearing ~or the tube
22 and accommodates not only rotation but also limited
tilting movement. The tube 22 also carries a direction
indicator cam 32 and a steering lock
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.-L~?7~
1 casting 34 for receiving the latch o-E a steering lock 36.
2 A shroud 38 carried by the bracket 26 covers the upper
3 part of the assembly while the lower part is housed within
4 a flared casing 40 fixed to the floor 140
A length A of the tube 22 is formed to have a precisely
6 dimensional internal surface exactly interfitting with the
7 rod 24, and the top section of the rod 24 which is received
~ in the length A in normal u e, as seen in Figure 1, is coated
9 with a low friction material, preferably a polytetrafluoroe-
thylene compound of which Dupont's Teflon is an example.
i r~ 11 Below this, a length B of the tube is opened out to give a
12 m2ximum clearance of 0.5 mm. In this way, the use of rela-
13 tively expensive tube having an accurately-sized interior
14 surface over the whole of its length is avoided, while still
giving good coupling for ste~riny.
16 The lengths A and B are suitably formed as shown in
17 Figure 40 The tube 22 is initially slightly underrsize. The
18 section which is to orm the length A is positioned in a die
19 42 and a punch 44 is dri~en into the tube 22~ The punch 44
has a first portion 44a whose surface conforms to the desired
21 configuration of the length A, and a larger portion 44b for
22 forming ~he length B.
23 If necessary, the rod 24 may be machined accurately
24 to size on only the corresponding length.
In Figure 1, the line C d~notes the axis of the
26 rod 24 and tube 22 with the cab tilted, the position of the
27 top of the rod 24 being indicated at D, while the line E
28 shows the limit of movement of the members in the opposite
29 direction during tilting.
~adc~
1 In assembly of the vehicle, the tub~ 22 with steering
2 wheel 18 attached is assembled with the direc~ion indicator
3 cam 32, the steering lock casting 34, and the bracket 26 and
4 bearing body 30. This assembly is then positioned with the
tube 22 received on the rod 24, and the bracket 26 is bolted
6 to the cab body. -
7 The upper member may be a rod and the lower a coopera-
8 ting ~ube, or both may be formed by tubes. Sections other
9 than square may be used and a driving connection may be en-
sured by means other than the cross-section of the members,
: 11 e~g. interfitting pins and slotsO
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