Steering damper in and for vehicles

A steering damper particularly for a bicycle which is integrated into the bicycle. The damper includes a housing closed at the top by a cap from which sidewalls extend and at the bottom. The housing contains a damping medium. Within the housing thee is a dam connected to the housing and a single vane connected to a shaft which passes through the housing. There is an opening in the shaft which communicates with the vane to circulate the medium during the damping when the bicycle departs from the path in which it is being directed and during the suppression of the damping when the bicycle returns to the path along which it is directed. The effective cross-section of the opening in the shaft is of sufficient magnitude to permit unrestricted flow of the medium. The housing and dam are supported within the steer-tube by the clamp from the steer-stem and are connected to the clamp by a tapered bearing rotatably with the steer-tube as the steer-tube is rotatable by the handlebars. The vane and shaft are not rotatable. Rotation of the dam on departure of the bicycle from its directed path pressurizes the medium between the dam and vane by flow through the shaft producing the damping and return of the bicycle produces flow of the medium through the vane and shaft suppressing the damping.

FIELD OF INVENTION 
This invention relates to vehicles and it has particular relationship to 
bicycles. It is to be understood that, to the extent that the principles 
of this invention are adapted to other vehicles than bicycles, for 
example, motorcycles, or even automobiles or trailer couplings, such 
adaptation is to be regarded as within the scope of equivalents of this 
invention. 
DESCRIPTION OF THE PRIOR ART 
Application Ser. No. 08/392,516 is typical of the prior art. Among the 
modifications which this invention discloses is a vehicle having 
integrated therein a steering damper which operates to damp the movement 
or rotation of the chain including the handlebars, steering stem, 
steer-tube, and steerable wheel when the handlebars are displaced from 
center and to suppress the damping when the handlebars return to center. 
The steering damper has a container or housing containing a damping fluid 
within which there are a dam and a plurality, usually two, of vanes. The 
housing is closed by a cap and a base. The dam is connected to, or 
integral with, the housing. A shaft passes axially through the housing. 
The vanes are connected to the shaft. The steering damper is mounted in 
the steer-tube with the housing and dam connected to the steer-stem 
rotatable with the steer-stem and steer-tube as the stem and tube are 
rotated by rotation of the handlebars. 
The vanes and dam divide the housing into three compartments: a compartment 
of variable volume between the dam and one vane, a compartment of constant 
volume between the one vane and the other vane and a compartment of 
variable volume between the other vane and the dam. The vanes have one-way 
valves. 
When the handlebars are displaced from center, the housing and base are 
moved so that the compartment between one vane and the dam is reduced in 
volume. The valve in the vane is in the closed setting and pressure is 
impressed on the fluid in the compartment and the fluid is conducted 
through a small opening in the dam or shaft which does not materially 
reduce the pressure and the displacement of the handlebars and the chain 
connected to it is damped. On the return of the handlebars to center, the 
fluid flows into the constant volume compartment between the vanes via 
recesses, typically in the cap and/or base of the housing to accommodate 
the flow of fluid. The pressure on the fluid is reduced and the damping is 
suppressed. 
The apparatus disclosed in application '516 has performed highly 
satisfactorily. However, the two vanes and the recesses impose a 
substantial cost of manufacture and complicate the operation of the 
steering damper. 
It is accordingly an object of this invention to overcome the 
above-described deficiencies of the prior art and to provide a steering 
damper adapted to be integrated in a vehicle which steering damper shall 
include only one vane and shall not require the recesses and shall avail 
effective control of the vehicle. 
SUMMARY OF THE INVENTION 
In accordance with this invention, there is provided a steering damper 
having a single vane. The vane and the dam define two compartments, one 
between the dam and the vane on one side and the other between the vane 
and the dam on the opposite side. The vane has one-way valves. Typically, 
each valve includes an opening in the vane which is covered by a resilient 
plate which normally holds it closed by the spring action of the plate. In 
operation, each valve is held closed by the pressure of the fluid in its 
corresponding compartment and opened by the pressure within the vane and 
relaxation of the pressure in corresponding compartment as the pressure of 
the fluid is affected by the position or rotation of the handlebars. 
There is also a shaft connected to the vane. The shaft has a first 
generally transverse opening, considered a damping passage which connects 
the compartments. When the handlebars are displaced from center, the dam 
is moved relative to the vane reducing the volume of one compartment and 
exerting pressure on the fluid in this compartment, closing the valve in 
the vane which is in this compartment. The fluid flows through the 
opening, but the opening is of such low effective cross-sectional area 
that the displacement of the handlebars is damped. The damping rate can be 
set by adjusting the effective cross-sectional area of the opening in the 
shaft. It is within the scope of this invention that this opening in the 
shaft can be eliminated and the desired damping rate can be achieved by 
appropriately sizing the numerous fluid leak paths around the shaft, vane 
and the dam or through the dam. 
The shaft has a second generally transverse opening which may be regarded 
as the free return passage. This opening is connected between the vane, 
one-way valves and a compartment when the handlebars are turned 
sufficiently with respect to the center position. When the handlebars are 
returned to center, the dam is retracted from the vane within which it has 
exerted pressure on the fluid in one compartment. Fluid from the second 
compartment whose volume is being reduced flows through the second 
opening, the vane opening and the valve which was closed and into the one 
compartment. Preferably, the effective cross-sectional area of this second 
opening is large enough so that the flow of fluid through this opening is 
substantially unrestricted and fluid pressure is substantiall unaffected 
and the damping is suppressed. 
During the first phase of operation while the handlebars are displaced from 
center, the first valve in the vane is held closed by the fluid pressure 
as the dam approaches the vane in the first compartment and the fluid 
flows through the first opening in the shaft into the second compartment. 
The handlebars are damped as they move away from center. The fluid in the 
second compartment is supplemented from a reservoir in the steering 
damper. This purpose is served by an axial opening in the end of the shaft 
which is in communication with the second opening. Fluid circulates from 
the reservoir through the axial opening in the shaft's end which is 
connected to the shaft's transverse second opening. For return from the 
second transverse opening, there are two paths: one through the vane and 
the other directly through the end of the transverse opening remote from 
the vane valve. The second path offers lower resistance than the first 
path. The second compartment receives the needed fluid while it is 
expanded. In the absence of this feature, the second compartment would 
contain a partial vacuum causing the handlebars to spring back. By the 
connection of the reservoir through the bore in the end of the shaft with 
the second opening in the shaft, the shaft and the one-way valves in the 
vane are able to provide the two functions of feeding the expanding 
compartment with the needed fluid from the reservoir as the handlebars 
turn away from center and providing the suppression of damping the 
handlebars return to center. 
During the second phase of operation when the handlebars are returned to 
center and the first compartment is expanded and the second compartment is 
contracted, the first valve is opened and fluid circulates freely from the 
second compartment where the fluid is under pressure by the retracting dam 
through the second opening in the shaft, the vane and the first valve and 
into the first compartment which expands, suppressing the damping. The 
damping is suppressed until the second opening in the shaft is closed as 
it passes the dam. The diameter of the second opening in the shaft can be 
smaller than the remaining width of the bore of the dam to aid in 
eliminating a potential suppression of damping when the handlebars are 
initially turned away from center. During the return of the handlebars to 
center, the second valve may be closed or open depending on the pressure 
differential across it. The one-way valves in the vane can be integrated 
into the shaft eliminating the need to adapt the vane for the valve's 
function. 
The words "fluid" "medium" are used of the interchangably in this 
application. The use words and "damping fluid" and "damping medium" in 
this application and in its claims are intended to include within their 
scope media of any appropriate type including oils, gases, air and 
elastomers such as sponges and the like.

DETAILED DESCRIPTION OF EMBODIMENT 
The apparatus shown in the drawings is a steer-tube/steer-stem type bicycle 
603 including a frame 353 and handlebars 355 extending from a steer-stem 
357. A clamp 359 extends integrally from the steer-stem 357 to clamp the 
steer-stem to a steer-tube 361 (FIG. 2). The steer-tube 361 is connected 
by clamp 363 to fork 365 which is connected to steerable wheel 33. The 
steer-tube 361 extends through a head 367 which is an integral part of the 
frame 353. The handlebars 355, steer-stem 357 and steer-tube 361 and the 
parts connected between the steerable wheel and the steer-tube 361 are 
rotatable on bearings 371 (FIG. 6) (only upper bearing shown) to steer the 
bicycle 603 through the steerable wheel. The moving race 373 of bearing 
371 is secured to, or integral with, the steer-tube 361 and fixed race 375 
is secured to, or integral with, the head 367. 
The apparatus shown in FIGS. 1, 2 and 6 includes a steering damper 601 
mounted in the steer-tube 361 of bicycle 603 (FIGS. 1 and 2). The steering 
damper 601 includes a housing 605 closed at the top by a cap 607 from 
which sidewalls 609 extend integrally (FIG. 6). The housing 605 has a 
threaded bottom closure 611 which is screwed into the sidewalls 609. 
The cap 607 includes a hexagonal or otherwise flat-sided surface 613 (FIG. 
2) on a radially extending projection 615 (FIG. 6). The steering damper 
601 is supported on the clamp 359. A tapered-lipped bushing 616 is 
interposed between the projection 615 of the cap 607 and the clamp. The 
projection 615 and the bushing 616 constitute a soft bearing for the 
damper 601. The cap 607 includes an axially projection 617 extending from 
its periphery above radial projection 615. The interior of the housing 605 
is defined between the cap 607, sidewalls 609 and closure 611. 
The steering damper 601 (FIG. 6) includes a dam 627. The dam 627 is 
generally in the shape of a segment of a hollow cylinder extending 
substantially over its maximum angle consistent with structural and 
manufacturing demands, typically 80.degree.. It is mounted in the steering 
damper 601 coaxially and in sliding engagement with the sidewalls 609 and 
its upper base in engagement with the inner surface of the cap 607. The 
dam 627 is secured to the housing rotatably therewith by dowel pins 629 
between the abutting surfaces of the cap 607 and the dam 627 (FIG. 6). A 
generally circular annulus 631 extends from the bottom of the dam and a 
cylindrical skirt 633 extends from the annulus. The skirt 633 and the 
annulus 631 define a reservoir 635. A diaphragm 637 is secured between the 
bottom of the skirt 633 and the upper surface of the base 611 of the 
container. The diaphragm 637 serves to absorb pressure differentials of 
the fluid with which the damper 601 is filled during temperature and 
operating cycles. 
The tapered bearing 616 is rotatable with the clamp 359 and thus with the 
steer-tube 357 as the steer-tube is rotated by the handlebars 355. The 
tapered bearing serves as a connection between the clamp 359 and the cap 
607 and through the cap with the sidewalls 609 and the dam 627. Through 
this connection, the cap 607, the side-walls 609 and the dam 627 are 
rotated in synchronism with the handlebars. The tapered bushing may also 
be fitted between the inner surface of the steer-tube 361 and the steering 
damper to rotate the dam in synchronism with the handlebars. 
The steering damper 601 also includes a shaft 641 (FIGS. 6, 7) coaxial with 
the housing 605, and also a vane 643. The shaft 641 and the vane 643 are 
secured together by dowel pins 645. The shaft 641 is generally cylindrical 
but may have a flattened outer surface 647 in the form of a keyway (FIG. 
2B) as in shaft 648 of the modification shown, which engages a 
corresponding flattened inner surface 649 in the form of a key of the vane 
650. There are cooperative openings in shaft 641 and vane 643 as shown in 
FIG. 2A for engagement by the dowel pins 645 or threaded openings in shaft 
648 of the modifications shown in FIG. 2B and vane 650 for engagement of a 
screw 654. The shaft 641 also has transverse openings 651 and 653. The 
opening 651 is in communication with a transverse opening 652 in the vane 
643 (FIG. 8). The opening 653 serves to conduct fluid when the fluid in 
the steering damper is under pressure. The opening 651 is of greater 
effective cross-section than the opening 653 more readily transmitting 
medium. The effective cross-sectional area of opening 651 should be such 
that flow of medium through this opening in the operation of the steering 
damper is substantially unrestricted. 
The vane 643 is generally a sector of a cylinder whose outer surface 655 
has a radius of curvature substantially close to that of the inner surface 
of the sidewalls 609 and is mounted in the housing 605 with the sidewalls 
609 slidable relative to the vane (FIGS. 8, 8A). The vane 643 has valves 
657 and 659 on its circumferential ends. Each valve includes a resilient 
plate 661 which may be regarded as a gate, secured at one end to the 
circumferential surface by a screw 663 (FIG. 6). Each plate 661 covers an 
opening 665 in the vane which is in communication with the opening 651 
(FIG. 8). The plate 661 by its spring action normally closes the valve. 
When pressure is impressed on the medium in a compartment, plate 661 holds 
valve 657 or 659 closed, blocking flow of fluid through openings 665 (FIG. 
8), 652 and 651 in the vane 643 and shaft 641. The pressure of the medium 
inside the vane 643 is in a direction to open the other valve 659 or 657 
but may not be sufficient to overcome the resilient force of plate 661. It 
is to be understood that, instead of normally closed valves 657 and 659, 
normally open one-way valves may be used in the practice of this 
invention. With normally open valves, the valve in the compartment in 
which the pressure is impressed is closed by the pressure while the other 
valve remains open. At its end abutting reservoir 635, shaft 641 has an 
axial opening 660 in communication with the transverse opening 651 in the 
shaft 641 (FIG. 6). 
The shaft 641 is mounted substantially coaxially with the sidewalls 609 and 
with the vane 643 extending circumferentially. A seal 670 is interposed 
between the outer surface of the shaft 641 and the cap 607 extending into 
a circular slot 672 in the head. The area of the passage for the fluid 
through opening 653 in the shaft 641 can be set by a screw 676 with a 
knurled head 678 which meshes with a thread in the shaft 641. The 
magnitude of the damping pressure is thus controlled. The control may be 
affected as disclosed with reference to FIGS. 2A and 2B of application 
Ser. No. 08/592,516 by a ball (442) carried by a cantilever (444) 
connected to screw 677. 
At its end at reservoir 635, shaft 641 has an axial opening 660 which is in 
communication with transverse opening 651. During displacement of the 
handlebars when pressure is applied to the medium in one of the 
compartments, the medium in the other compartment is supplemented by flow 
from the reservoir 635 through the axial opening 660 in the shaft 641. At 
the junction with the transverse opening 641, the medium can flow through 
two parallel paths into the other compartment which is expanding: one path 
through the corresponding valve 657 or 659 and the other through the end 
of the transverse opening 651 remote from this valve. The latter path 
offers the lower resistance. 
The steering damper 601 replaces the bolt and cap which applies pressure to 
the bearings 371 in prior-art bicycles. (See FIG. 2 and accompanying 
description in application '516). The steering damper 601 is connected by 
stud 393 secured to the star nut 377, which is suspended from the 
steer-tube 361. The star nut 377 and the stud 393 not only add to the 
support of the steering damper but, also, apply pressure to the bearings 
371 and the soft bushing 616 provided by the projection 615 effectuating 
the synchronous rotation of the housing 605 and dam 627 with the 
handlebars 355. 
A clamp assembly 671 secures the unit including shaft 641 and vane 643 from 
rotating with the unit including housing 605 and dam 627. This clamp 
assembly has an arm 673 having a yoke 675 including internal splines at 
the upper end. The yoke 675 engages the shaft 641 near the top; the shaft 
has splines 677 (FIG. 7) which match the splines in the yoke. The clamp 
assembly also includes a bracket 679 having a yoke 681 from which a 
projection 683 extends (FIG. 3, 6). The yoke 681 encircles and is secured 
to the lower fixed race 375 of the bearing 371 on which the steer-tube 361 
is rotatable. The arm 673, near its lower end, engages in an opening 685 
on projection 683 through a bushing 687. Additionally, hole 785 of lower 
clamp 671 may be elongated in direction shown (FIG. 8) to substantially 
decrease the radial load on shaft 641 during operation when shaft 641 is 
not exactly concentric with bicycle's steering axis of rotation 
The inner surface of the dam 627 in contour matches, i.e., is substantially 
close to the radius, or curvature of, the shaft 641 (FIG. 8). This inner 
surface of the dam 627 extends over a greater angle than the openings 651 
in the shaft 641 as shown in FIG. 8. This feature prevents unstable 
operation when the bicycle is moving linearly by overlap of the dam 627 by 
the opening 651 which would result in undesirable suppression of the 
damping on the initial rotation of the handlebars. Since the lower bearing 
375 is ultimately secured to the frame 353, the shaft 641 and vane 643 are 
prevented from rotating with the housing 605 and dam 627. The arm 673 of 
the clamp assembly 671 serves as a stop for projection 617 preventing 
impact of the vane 643 with the dam 627. 
FIGS. 4 and 5 show a modifications of the lower part of the clamp assembly. 
In the modification of 691 of FIG. 4, the bearing 693 and the bracket 695 
are shown as an integrated assembly. In the modification 697 shown in FIG. 
5, the bracket 698 is of relatively small thickness and in use is secured 
to the lower race 703 of the bearing 705. 
The embodiment 709 of the invention shown in FIG. 7 is, to a large extent, 
similar to the modification disclosed in FIG. 6. Only the difference 
between the two modifications will be described. 
The dam 711 of the embodiment shown in FIG. 7 has arms 715 extending 
inwardly. The vane 713 is nested between the arms 715 being in the 
cylindrical section bounded by the arms 715, the sidewalls 609 of the 
housing 605 and the shaft 641. The dam 711 is secured to the housing 605 
by a key 717 extending through coextensive keyways 719 and 721 in the cap 
723, dam 711 and sidewalls 609. The cap 723 is otherwise similar to the 
cap 607 of the embodiment shown in FIG. 6. A hollow cylindrical member 725 
is supported on the bottom closure 611. A diaphragm 727 is secured between 
the end of the cylindrical member 725 and the closure extending into the 
reservoir 635 defined by the cylindrical member and the closure 611. As in 
the embodiment shown in FIG. 6, the reservoir 635 is connected to the 
opening 651 in shaft 641 through the axial opening 660 in the shaft. There 
are ball bearings 729 between the housing 605 and the shaft 641. The one 
race 731 is connected to the shaft and the other race 733 is connected 
through the dam 711 to the sidewalls 609 of the housing 605 which rotates 
relative to the shaft. The races 733 of the bearings 729 are structured so 
that the bearings exert radial pressure. Thus the bearings 729 applied 
radial support to the shaft which makes the unit operate smoother. If 
there is a side load on the shaft and no bearing, the surface of the dam 
rubs on the shaft. This has been a problem for years in rotary dampers. 
The dam may be made completely from an appropriate bushing material such 
as "Delrin, TM" eliminating bearings 729. 
The operation of the embodiments shown in FIGS. 2, 6 and 7 will now be 
described with reference to FIGS. 8 and 8A. The shaft 641 at its outer 
surface, the vane 643 and the dam 627 define compartments 741 and 743. 
FIG. 8 shows the relative position of vane 643 and dam 627, i.e., directly 
opposed from one another when the bicycle 603 is steered along a straight 
line. This is an arbitrary position. 
The dam 627 extends over and overlaps the opening 651 in the shaft 641. The 
vane 643 extends over the opening 651, 180.degree. from the dam in the 
FIG. 8 setting. The vane is in communication with the opening, but flow of 
fluid is blocked by the dam. 
Now, with reference to FIG. 8A. Assume that the handlebars have turned so 
that the dam 627 is turned counterclockwise in the direction of arrow 745 
exerting pressure on the fluid in compartment 741. Valve 657 is held 
closed and fluid under pressure is forced through opening 653 (FIG. 6) in 
shaft 641 into compartment 743. Valve 659 is opened and fluid circulates 
from reservoir 635 (FIG. 6) through openings 660 and 651 in shaft 641 and 
valve 659 to aid in the flow into expanding compartment 743. The opening 
653 in shaft 641 is of small diameter or cross-sectional area, typically 
0.080-inch. Ultimately, this diameter does not restrict flow until reduced 
by screw 676 (FIG. 6). Restricting the flow from compartment 741 into 
compartment 743 damps the displacement of the handlebars. The conduction 
of fluid from compartment 741 into compartment 743 may be effected in 
other ways than by conduction through an opening in the shaft 641. For 
example, there may be a channel through dam 627 or elsewhere. 
Now, assume that the handlebars are returning from displacement. Dam 627 
moves in the direction of arrow 747. The fluid in compartment 743 is under 
pressure and valve 659 is held closed and valve 657 is opened and fluid 
circulates from reservoir 635 through openings 651 and 660 in shaft 641 
and valve 657 to aid in the flow into expanding compartment 741. Fluid 
circulates from compartment 743 through openings 651 in the shaft 641 
through valve 657 into compartment 741. Opening 651 is of substantially 
larger diameter, or effective cross-section area, than opening 653, 
typically 0.140-inch and does not restrict the flow of the fluid or 
medium. Essentially, the pressures in compartments 741 and 743 are 
equalized. The fluid is not compressed and the handlebars on the returned 
rotation are not damped. 
Within the scope of this invention, the difference in the pressure 
impressed through the openings 653 and 651 in shaft 641 may also be 
achieved by openings in shaft 641 of the same cross-section, but with the 
opening corresponding to opening 653 in cross-section restricted by screw 
676. The circulation through the opening 651 in shaft 641 prevents the 
buildup of pressure in the decreasing compartment during the return 
movement of the handlebars, which would damp the return movement of the 
handlebars. 
FIG. 9 shows another embodiment 760 of this invention. In this case, 
one-way valves 761 and 763 are in the shaft 765. The advantage of this 
embodiment is that the vane 767 requires no passages. FIG. 9 shows the 
steering damper as it is set when the bicycle is moving linearly. This is 
an arbitrary position. The dam 769 extends over and overlaps the opening 
771 in the shaft. With the handlebars displaced from center in one 
direction, the housing 773 and dam 769 are rotated counterclockwise in the 
direction of the arrow 775. When the vehicle departs from linear motion, 
valve 761 is closed and the fluid in compartment 777 is pressurized 
producing damping. The fluid flow into compartment 779 is through a hole 
(not shown) in shaft 765 and through valve 763 in shaft 765. On the return 
of the handlebars, valve 761 is opened and the fluid is circulated through 
opening 771 and the damping is suppressed. An anlogous operation takes 
place if the handlebars are displaced to produce clockwise movement of the 
dam 769. 
FIG. 10 shows a steering damper 801 including a dam 803 and head 805 as an 
integrated structure. The advantage of this modification is that the 
housing is a cylinder 807 instead of the combined structure in which the 
housing 605 and cap 607 (FIG. 6) are integral. The head 805 has a 
projection 809 which is adapted to limit the rotation of the unit 
including the dam 803 and housing 805 by engagement with a clamp such as 
clamp 671 of FIG. 6. 
The housing 807 has internal thread shown in FIGS. 11 through 14 for 
engaging thread 813 and 815 on head 805 and skirt 817. The skirt defines a 
reservoir 819 which is in communication with an opening in shaft 821 
through an axial opening 829 in the inner end of shaft 821 as in FIG. 6. 
The shaft 821 engages sleeve bearings 823 in the head 805 and dam 803. The 
vane 825 is seated between the head and the projection extending from the 
dam and is secured to the shaft 821. 
The steering damper 831 is of the doughnut type generally analogous to the 
dampers disclosed in applicant's U.S. Pat. No. 5,492,033. The damper is 
adapted to be mounted coaxially with the steer-tube (not shown) of the 
bicycle and to be rotated with the steer-tube as the steer-tube is rotated 
by the handlebars (not shown) or undesirably by the steering wheel (not 
shown). 
The damper 831 includes an outer closed housing 833 containing a damping 
medium and fixed to the outer race of the steering head bearing (371, FIG. 
6). Within the housing 833 there is an annular collar 835 having a groove 
837 between what may be regarded as flanges 839 (FIG. 13). There is also a 
vane assembly 841 including a vane 843 extending integrally from an 
annulus 845. The annulus 845 is coaxial with the collar 835 with its inner 
periphery abutting the peripheral rim of the flange 839 forming with the 
groove 837 a passage 847 for the damping medium. The passage 847 is in 
communication with an opening 849 in the vane 843 through channel 851. The 
opening 849 in the vane terminates in one-way valves 853 and 855. The 
valves 853 and 855 have on their external surfaces 857 resilient plates 
which are normally held closed by their resilience, but are opened by 
pressure of the medium counteracting the resilience. Generally, 
diametrically opposite the vane 843, the annulus 845 has an opening 859 in 
medium flow communication with the annular groove or passage 847. The 
effective cross-section of the groove is such that the flow of the medium 
which enters through opening 859 is substantially unrestricted. 
The damper 831 also has a dam 861 generally in the form of a segment of a 
circular cylinder whose internal surface 863 has substantially the same 
curvature as the external surface of the annulus 845. The dam 861 may have 
the same curvature as the internal surface of the housing. The unit 
including the vane assembly 841 and collar 835 forming the groove 847 and 
the unit including the housing 833 and dam 861 are rotatable one relative 
to the other. 
Between the vane 843 and the dam 861, compartments 871 and 873 are defined. 
The dam has an opening 875 through which the compartments 871 and 873 are 
in medium communication. 
When integrated with a bicycle, the steering damper 831 is mounted with the 
units 833-861 and 835-857 substantially coaxial with the steer-tube of the 
bicycle, with one unit connected to the frame and the other connected 
rotatable with the steer tube. The unit connected to the steer-tube is 
rotatable with the steer-tube and thus synchronously with the handlebars. 
Specifically, the housing unit 833-861 may be connected to the frame and 
the vane unit 835-847 rotatable with the steer-tube. With the bicycle 
moving linearly, the damper is in the state shown in FIG. 11 with the dam 
861 overlapping the opening 859 and not allowing interchange of medium 
between compartments 871 and 873 via passages in vane assembly 841. It is 
assumed that the unit 835-857 is connected to the steer-tube and that the 
handlebars are rotated clockwise in the direction of the arrow 883. The 
medium in compartment 871 is subjected to pressure, valve 853 is closed 
damping the rotation of the handlebars. The medium is forced by the 
pressure to flow through opening 875 in the dam 861, but the opening is of 
small effective cross-sectional area and the pressure in compartment 871 
and the damping is maintained. 
Now assume that the handlebars are returned to center. The pressure in 
compartment 871 is reduced and valve 853 is opened. The medium now flows 
from compartment 873 through opening 859, passage 847, passages 851 and 
849, valve 853 into compartment 871 which is expanding. The effective 
cross-sectional area through opening 853 groove 847, channel 851 and 
opening 849 is such that the flow of medium is substantially unrestricted 
and the damping is suppressed. 
It is to be understood that within the scope of this invention, the 
steer-tube 361 may serve as housing for the steering damper as disclosed 
in FIG. 29, application '516. But the resulting damper would, aside from 
the housing, have the structure disclosed in FIGS. 6 or 7 including one 
vane cooperative with a shaft structure internally to circulate fluid and 
may have an external clamp for suppressing rotation of the vane and shaft. 
Also, components of FIG. 11 may be integral with steer-tube and head of 
bicycle as disclosed in U.S. Pat. No. 5,492,033. 
While preferred embodiments of this invention are disclosed herein, it is 
understood that many modifications thereof are feasible. This invention is 
not to be restricted except insofar as is necessitated by the spirit of 
the prior art.