CA1252035A - Sliding pushbar mechanism for wheelchair rims - Google Patents
Sliding pushbar mechanism for wheelchair rimsInfo
- Publication number
- CA1252035A CA1252035A CA000539692A CA539692A CA1252035A CA 1252035 A CA1252035 A CA 1252035A CA 000539692 A CA000539692 A CA 000539692A CA 539692 A CA539692 A CA 539692A CA 1252035 A CA1252035 A CA 1252035A
- Authority
- CA
- Canada
- Prior art keywords
- pushbar
- wheel
- tongue
- wheelchair
- rim
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
Abstract In the operation of wheelchairs, it is common to have a manual pushbar mechanism that is connected through an arrangement of gears, cogs and axles to drive the wheels of the wheelchair and that may be pushed by the occupant of the wheelchair to propel both the wheelchair and its occupant. In this invention, a new type of manual pushbar mechanism is disclosed. It operates by transmitting rotational force to the main wheels. The pushbar mechanism is returned to its original position after a stroke that transmits the rotational force by sliding back around the wheels. The engagement of a tongue from the pushbar mechanism to the wheels is used to drive the wheels, while its disengagement on the return stroke is used to allow the wheels to continue rotation in the same direction. A switching control is used to engage a different tongue, having a reverse orientation with respect to the wheel, in order to propel the wheelchair in a reverse direction.
Description
~S2~5 SPECI FICATION
FIELD OF THE INVENTION
This inven-tion relates to occupant-propelled wheelchairs. In particular this invention relates to such wheelchairs that have a mechanism to translate manual force into a rotational force to drive the wheels along the ground.
BACKGROUND OF THE INVENTION
Many mechanisms have been invented to allow the occupant oE
a wheelchair to propel the wheelchair by the application oE
a manual force. In U.S. Patent number ~,471,972, for example, a hand-pedal mechanism is shown that translates a rotational motion by the hands to the wheels by means of a series of gears and chains or belts and pulleys. A differen-t type oE mechanism for propelling a wheelchair is shown in U.S. Patent 2,643,898, which discloses an arm tha-t may be oscillated by hand to drive the -traction wheel of a wheelchair in a ra-tchet-like fashion. U.S. Patent numbers 4,453,729 and 4,460,190 show mechanisms that combine manual pushbars with a chain drive to propel the traction wheels of a wheelchair. Another type of propelling mechanism is disclosed in U.S. Patent number 3,309,110. There a propelling bar is oscillated in order to move a bar that in turn oscillates about the radius of the trac-tion wheel and transmits its force to the wheel.
None of the prior technology discloses the mechanism of -the present invention.
:~25~ 5 SUMMARY AND OBJECTS OF THE INVENTION
This invention involves a very simple yet ingenious means of transmitting manual force Erom a pushbar to the -traction wheel of a wheelehair. The means enables the opera-tor to avoid direct contact by his hand on -the traction wheel itselE, or on any concentric wheel. Friction that would thereby be generated as the operator grips and regrips the moving wheels to apply additic>nal spin is thereEore avoided.
With the mechanism of -this invention, the oceupant of the wheelchair ean propel the ehair by means of an oscillating, partially ro-tational motion of the hands, from a eomEortable rowing stance in the wheelchair. The invention is different from the examples given above, however, in -that the mechanism is very simple, requiring no gears, ehains, pulleys, and belts. The mechanism of this invention aeeomplishes its task by alterna-tely gripping and sliding upon the rim of the traction wheel, or upon the rim of a eoneentrie push-wheel, in order to alternately propel and reeover for another stroke oE propulsion to the wheel. A
matehing pair oE -these mechanisms can be used to drive both the main wheels of a typical wheelchair. It is the objec-t of this invention to provide a mechanism to propel a wheelchair by manual means as described above.
GENERAL DESCRIPTION OF T~IE INVENTION
This invention accomplishes its objects by means of a housing that is slidably at-tached to a portion of the rim of ~25~3~
a wheel on a wheelchair. Inside -the housing is at least one tongue that may be pressed upon the rim by a pushbar to provide traction be-tween the pushbar and the rim. The mo-tion on the pushbar to create this traction is one parallel to the circumference of the wheeLchair. The mo-tion therefore causes an ini-tial gripping between the assembly oE the pushbar, housing and tongue, and the wheel, and then causes the wheel to rotate.
When the assembly has powered the wheel for a Eraction of its circumference, the assembly must be pulled back before the user loses his grip on it and before i-t rotates down to the ground. The inven-tion provides for the assembly to coast back along the rim, without braking the wheel, which continues -to ro-tate in the direc-tion in which it had been pushed by -the assembly, by means of an automatic lifting of the gripping tongue on the return stroke of the pushbar.
~he lifting of -the tongue can be accomplished by a spring between the housing and the end of the tongue, that pushes it back and ofE the rim in the absence of pressure from the pushbar on a powering stroke.
The return stroke can be made virtually frictionless by using ball bearings in tracks within the housing to encicle -the rim of the wheel, excepting only the inner surface of the rim, from which spokes to the center of the wheel typically prGtrude. The ball beacings also serve to keep -the assembly in the proper posi-tion on the rim of ~he wheel.
A Erame affixed to the side oE -the body o-E -the wheelchair defines the Eraction of the circumference of the wheel around which the assembly can travel back and forth. When the pushbar assembly bumps in-to this over-travel guard frame on a power stroke, it simply ceases -to apply pressure to the tongue and the rim of -the wheel coasts through the assembly, con-tinuing to rotate due to inertia. Alternatively, a chain at-tached -from the assembly to -the body of -the wheelchair could be used to restrict the distance that the assembly could travel around -the circurnEerence of the wheel.
The above described assembly should be used in pairs, one assembly for each oE the two traction wheels on a typical wheelchair. Equal power could thus be simultaneously applied to both wheels, allowing the wheelchair to move s-traight ahead, rather than turning in a circle as would happen if more power were applied to one wheel than the other. The pair of such assemblies would be independent, however. That is, they would allow differing power to be applied to each in order to ~acillitate turning.
The manual pushbar assembly can be made to apply power to the wheel in a reverse direction, and -to slide back in the opposite direction, by means of having a second tongue arrangemen-t, symetrical with the first tongue abou-t the end of the pushbar, within the housing. A cog on the end oE the pushbar, -that can be retrac-ted w:i-th a control button or lever would determine whether the housed end of the pushbar pressed the -tongue for forward motion, or the o-ther tongue Eor backward motion of the wheel, when the pushbar was moved in opposing directions. The coasting back-stroke would correspondingly be switched. The back-stroke would in both ~;~52~35 cases result in the cog on the end of -the pushbar pressing on a bummper cog afflxed -to the housing rather than the other tongue, until the cog was retracted to sea-t the pushbar on the other side oE the bumper cogO
An alternative reversing mechanism would have cavities in the pushbar, through which a con-trolling inner block would be able to directly engage the appropriate tongue.
The block would be adjustable into an up or down position within the housing. There would be two cavities in the block, at differen-t heights and on opposite sides, such that in one position, the Eorward tongue would enter a cavity rather than being pressed by the block in the pushbar, and in the other position, the backward tongue would enter the other cavity rather than being pressed. ~he coastir.g back-stroke could thus occur between each powering stroke, with -the wheelchair continuing to move in the same direc-tion. After stopping the wheelchair, the reverse direction could be achieved by merely pushing a pushbutton to control the position of the block within the pushbar, and then continuing the rowing motion. Upon engaging the reverse position, the powering partial rota-tional stroke would be in the opposite direction, that is, in the same direction as the coas-ting stroke oE
the previous position. As a ~urther alternative, the reversing m~chanism could be comprised oE a single cavi-ty in the block, provided the orientation of the cavity could be changed such tha-t one or the other of the tongues could selectively be enveloped by -the cavi-ty, leaving the other tongue to be engaged for propulsion. Another variation would be to have the block and cavity reversing means on the outside of, or as part oE, the pushbar itself.
The assembly can be made to fit over the main traction wheel of a wheelchair, or can be made to -Eit over an outer concentric push~wheel that is afEixed or itself slidably at-tached to the main traction wheel. In the case oE being fi-tted over a pushwheel, grooving in the surEace of the rim and of -the tongue may be required to enable the -tongue to sufficiently grip -the rim on a powering stroke by the pushbar assembly.
The assembly can also be fitted with a braking device. For example, a brake pad could be affixed to the inside of the pushbar, to make contact with the rotating rim of a wheel, when the pushbar is pivotted toward the body of the wheelchair. Alternatively, the pushbar could be fitted with a flange that lifted a brake bar and pad to make contact with the rim of -the wheel, when the pushbar is lifted or pivotted toward the body of the wheelchair.
The pushbar could be straight or curved for enhanced comfort of pushing and pulling. A further option would be to have a two part pushbar, connected by a hinge -that allowed the angle of the part to be gripped by the user's hand to be adjusted. A tightening knob could be used to lock the preferred angle after adjustment.
This invention could be made as a kit for add-on installation to existing wheelchairs.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of an embodiment of -this invention.
~zs~
Figure 2 is a cross-sectional side view oE an embodiment of the pushbar, housing, and tongue assernbly of this invention.
Figure 3 is a cross-sectional front view of an embodiment of this invention.
Figure 4 is a top view of of an embodiment of this invention.
Figure 5 is a cross-sectional side view of an alterna-te form oE the pushbar, housing, and tongue assembly of thls invention.
Figure 6 is a cross-sectional front view of an alternate form of the braking mechanism oE this invention.
DETAILED DESCRIPTION
Referring to Figure 1, a side view of a wheelchair is shown. It has a back 2, an armrest 3, a seat 4, a footrest 5, front wheels 6, large ground-traction wheels 7, and push-wheels 8 that are concentric with and smaller than the main wheels 7. Attached around part of the rim 9 of the push-wheel 8 is the housing 10 of this invention. The pushbar 11 protrudes Erom the housing 10 up to a position at which an occupant oE the wheelchair could push on the pushbar 11 -to propel tha wheelchair. The over-travel guard 12 is attached to the armrest 3 and envelopes the area in which the p~lshbar 11 is meant to move. An alterna-te position 1~5~
13 is shown for the pushbar 11, reached by pushiny the end of pushbar 11 in a forward and downward direction Referring to Figure 2, the inside oE the housing lO is shown. The pushbar 11 is in a position to press or the forward tongue 18. When it does, the tongue 18 will be forced down by the shape of the housing 10 to contac-t and grip the rim 9 of the push-wheel 8. The push-wheel 8 will then rotate and the main wheel 7 will in turn rotate, thereby propelling the wheelchair. There are ball bearings 19 that allow the housing 10 to sli~e along the rim 9. A
spring 20 on the end of the tongue 18 lifts it off the rim 9 in the absence of a contrary force from the pushbar 11. A
flange 21 on the housing engages a corresponding, retractable cog 22 of the pushbar 11, in order to preven-t the pushbar 11 from driving the reverse tongue 23 on a back stroke by the occupant. By means of a lever or cable, the cog 22 can be retracted and released on the other side of the flange 21, in order to enable a reverse propell;ng motion to be imparted -to the wheelchair.
Referring to Figure 3, a cross-section shows the pushbar 11 with a handle 26, the angle of which can be adjusted for the comfort of the user by means of a hinge and tightening knob 27. The pushbar 11 enters the housing 10, which is slidably attached to the rim 9 of -the push-wheel by means of its shape and its ball bearings 19. A brake pad 28 is mounted on the pushbar 11, which has enough sideward play to allow the occupant to pivot the pushbar 11 toward the wheelchair body, thereby making the brake pad 28 contac-t the trac-tion rim of the main wheel 7. The over-travel guard 12 is attached -to ~Z5,~3~
the armrest 3, but it could alternatively be attached to another part of the Erame 29 of the wheelchair.
Referring -to Figure 4, a top view shows the housing 10, attached to the rim 9 of the push-wheel. The pushbar 11 and its handle 26 ex-tends Erom the housing to where the occupant can grip -the handle 26. The over-travel guard 12 prevents the pushbar 11 and housing assembly from rotating too far around the push-wheel. If the guard 12 were not there, the assembly could travel past -the point at which the occupant could grip the pushbar 11, and could even hit the ground.
The guard 12 is at-tached to the armrest 3. The back 2 and the seat 4 of the wheelchair are also shown.
Referring to Figure ~, an alternative means of switching between forward and reverse directions for the wheelchair is depicted. When the block 39 within the pushbar 11 is in the upper position (the position shown), the contact surface 30 will press upon the forward tongue 18, which will be guided by the shape of the inside of the housing 10 to press upon and rotate the rim 9. On the back-stroke, the spring 20 will lift the -tongue 18 off the rim 9 and allow the pushbar and housing assembly to slide on the ball bearings 19 backwards along the rim 9O As the pushbar is being pulled backwards, the block 39 does not engage the reverse tongue 23, because of the presence of the cavity 31. When the block 39 is put into a lower posi-tion by the occupant, hDwever, the surface 33 will engage the reverse tongue, while the cavity 34 will allow the coasting back-stroke without engaging -the forward tongue 18. There is a connector 32 to the pushbutton control means for switching the position of -the block 39. The pushbar is ;~2S~ 5 ro-tatably attached a-t 40 to the side of the housing 10. This attachment can be made to allow some sideways play in the posi-tion oE -the pushbar in order to enable the optional bra~ing movement described below.
Referring to Figure 6, the pushbar 11 is shown with a flange 35 at its end. ~pon a slight pivotting of the pushbar toward the occupant, the flanqe will lift the braking bar 36, making the braking pad 37 contac-t the underside of the rim 3.The braking bar 3~ is held in place by means of a slotted flange 38 on the housing 10 and is re-turned to its non-braking position by means of a spring 39 also mounted on the housing 10.
The within-described invention may be made in a variety of sizes and shapes and with a variety of accessories, For example, the tongues and housing could be shaped such that the tongues gripped the rim along an extended surface, rather than at a relatively sharp end area of the tongue, as shown in the Figures. The invention may be embodied in other specific forms without departing from -the spirit or essential characteristics thereof. The presently disclosed embodimen-t ~s thereEore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range oE e~uivalency of the claims are -thereEore intended to be embraced therein.
FIELD OF THE INVENTION
This inven-tion relates to occupant-propelled wheelchairs. In particular this invention relates to such wheelchairs that have a mechanism to translate manual force into a rotational force to drive the wheels along the ground.
BACKGROUND OF THE INVENTION
Many mechanisms have been invented to allow the occupant oE
a wheelchair to propel the wheelchair by the application oE
a manual force. In U.S. Patent number ~,471,972, for example, a hand-pedal mechanism is shown that translates a rotational motion by the hands to the wheels by means of a series of gears and chains or belts and pulleys. A differen-t type oE mechanism for propelling a wheelchair is shown in U.S. Patent 2,643,898, which discloses an arm tha-t may be oscillated by hand to drive the -traction wheel of a wheelchair in a ra-tchet-like fashion. U.S. Patent numbers 4,453,729 and 4,460,190 show mechanisms that combine manual pushbars with a chain drive to propel the traction wheels of a wheelchair. Another type of propelling mechanism is disclosed in U.S. Patent number 3,309,110. There a propelling bar is oscillated in order to move a bar that in turn oscillates about the radius of the trac-tion wheel and transmits its force to the wheel.
None of the prior technology discloses the mechanism of -the present invention.
:~25~ 5 SUMMARY AND OBJECTS OF THE INVENTION
This invention involves a very simple yet ingenious means of transmitting manual force Erom a pushbar to the -traction wheel of a wheelehair. The means enables the opera-tor to avoid direct contact by his hand on -the traction wheel itselE, or on any concentric wheel. Friction that would thereby be generated as the operator grips and regrips the moving wheels to apply additic>nal spin is thereEore avoided.
With the mechanism of -this invention, the oceupant of the wheelchair ean propel the ehair by means of an oscillating, partially ro-tational motion of the hands, from a eomEortable rowing stance in the wheelchair. The invention is different from the examples given above, however, in -that the mechanism is very simple, requiring no gears, ehains, pulleys, and belts. The mechanism of this invention aeeomplishes its task by alterna-tely gripping and sliding upon the rim of the traction wheel, or upon the rim of a eoneentrie push-wheel, in order to alternately propel and reeover for another stroke oE propulsion to the wheel. A
matehing pair oE -these mechanisms can be used to drive both the main wheels of a typical wheelchair. It is the objec-t of this invention to provide a mechanism to propel a wheelchair by manual means as described above.
GENERAL DESCRIPTION OF T~IE INVENTION
This invention accomplishes its objects by means of a housing that is slidably at-tached to a portion of the rim of ~25~3~
a wheel on a wheelchair. Inside -the housing is at least one tongue that may be pressed upon the rim by a pushbar to provide traction be-tween the pushbar and the rim. The mo-tion on the pushbar to create this traction is one parallel to the circumference of the wheeLchair. The mo-tion therefore causes an ini-tial gripping between the assembly oE the pushbar, housing and tongue, and the wheel, and then causes the wheel to rotate.
When the assembly has powered the wheel for a Eraction of its circumference, the assembly must be pulled back before the user loses his grip on it and before i-t rotates down to the ground. The inven-tion provides for the assembly to coast back along the rim, without braking the wheel, which continues -to ro-tate in the direc-tion in which it had been pushed by -the assembly, by means of an automatic lifting of the gripping tongue on the return stroke of the pushbar.
~he lifting of -the tongue can be accomplished by a spring between the housing and the end of the tongue, that pushes it back and ofE the rim in the absence of pressure from the pushbar on a powering stroke.
The return stroke can be made virtually frictionless by using ball bearings in tracks within the housing to encicle -the rim of the wheel, excepting only the inner surface of the rim, from which spokes to the center of the wheel typically prGtrude. The ball beacings also serve to keep -the assembly in the proper posi-tion on the rim of ~he wheel.
A Erame affixed to the side oE -the body o-E -the wheelchair defines the Eraction of the circumference of the wheel around which the assembly can travel back and forth. When the pushbar assembly bumps in-to this over-travel guard frame on a power stroke, it simply ceases -to apply pressure to the tongue and the rim of -the wheel coasts through the assembly, con-tinuing to rotate due to inertia. Alternatively, a chain at-tached -from the assembly to -the body of -the wheelchair could be used to restrict the distance that the assembly could travel around -the circurnEerence of the wheel.
The above described assembly should be used in pairs, one assembly for each oE the two traction wheels on a typical wheelchair. Equal power could thus be simultaneously applied to both wheels, allowing the wheelchair to move s-traight ahead, rather than turning in a circle as would happen if more power were applied to one wheel than the other. The pair of such assemblies would be independent, however. That is, they would allow differing power to be applied to each in order to ~acillitate turning.
The manual pushbar assembly can be made to apply power to the wheel in a reverse direction, and -to slide back in the opposite direction, by means of having a second tongue arrangemen-t, symetrical with the first tongue abou-t the end of the pushbar, within the housing. A cog on the end oE the pushbar, -that can be retrac-ted w:i-th a control button or lever would determine whether the housed end of the pushbar pressed the -tongue for forward motion, or the o-ther tongue Eor backward motion of the wheel, when the pushbar was moved in opposing directions. The coasting back-stroke would correspondingly be switched. The back-stroke would in both ~;~52~35 cases result in the cog on the end of -the pushbar pressing on a bummper cog afflxed -to the housing rather than the other tongue, until the cog was retracted to sea-t the pushbar on the other side oE the bumper cogO
An alternative reversing mechanism would have cavities in the pushbar, through which a con-trolling inner block would be able to directly engage the appropriate tongue.
The block would be adjustable into an up or down position within the housing. There would be two cavities in the block, at differen-t heights and on opposite sides, such that in one position, the Eorward tongue would enter a cavity rather than being pressed by the block in the pushbar, and in the other position, the backward tongue would enter the other cavity rather than being pressed. ~he coastir.g back-stroke could thus occur between each powering stroke, with -the wheelchair continuing to move in the same direc-tion. After stopping the wheelchair, the reverse direction could be achieved by merely pushing a pushbutton to control the position of the block within the pushbar, and then continuing the rowing motion. Upon engaging the reverse position, the powering partial rota-tional stroke would be in the opposite direction, that is, in the same direction as the coas-ting stroke oE
the previous position. As a ~urther alternative, the reversing m~chanism could be comprised oE a single cavi-ty in the block, provided the orientation of the cavity could be changed such tha-t one or the other of the tongues could selectively be enveloped by -the cavi-ty, leaving the other tongue to be engaged for propulsion. Another variation would be to have the block and cavity reversing means on the outside of, or as part oE, the pushbar itself.
The assembly can be made to fit over the main traction wheel of a wheelchair, or can be made to -Eit over an outer concentric push~wheel that is afEixed or itself slidably at-tached to the main traction wheel. In the case oE being fi-tted over a pushwheel, grooving in the surEace of the rim and of -the tongue may be required to enable the -tongue to sufficiently grip -the rim on a powering stroke by the pushbar assembly.
The assembly can also be fitted with a braking device. For example, a brake pad could be affixed to the inside of the pushbar, to make contact with the rotating rim of a wheel, when the pushbar is pivotted toward the body of the wheelchair. Alternatively, the pushbar could be fitted with a flange that lifted a brake bar and pad to make contact with the rim of -the wheel, when the pushbar is lifted or pivotted toward the body of the wheelchair.
The pushbar could be straight or curved for enhanced comfort of pushing and pulling. A further option would be to have a two part pushbar, connected by a hinge -that allowed the angle of the part to be gripped by the user's hand to be adjusted. A tightening knob could be used to lock the preferred angle after adjustment.
This invention could be made as a kit for add-on installation to existing wheelchairs.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of an embodiment of -this invention.
~zs~
Figure 2 is a cross-sectional side view oE an embodiment of the pushbar, housing, and tongue assernbly of this invention.
Figure 3 is a cross-sectional front view of an embodiment of this invention.
Figure 4 is a top view of of an embodiment of this invention.
Figure 5 is a cross-sectional side view of an alterna-te form oE the pushbar, housing, and tongue assembly of thls invention.
Figure 6 is a cross-sectional front view of an alternate form of the braking mechanism oE this invention.
DETAILED DESCRIPTION
Referring to Figure 1, a side view of a wheelchair is shown. It has a back 2, an armrest 3, a seat 4, a footrest 5, front wheels 6, large ground-traction wheels 7, and push-wheels 8 that are concentric with and smaller than the main wheels 7. Attached around part of the rim 9 of the push-wheel 8 is the housing 10 of this invention. The pushbar 11 protrudes Erom the housing 10 up to a position at which an occupant oE the wheelchair could push on the pushbar 11 -to propel tha wheelchair. The over-travel guard 12 is attached to the armrest 3 and envelopes the area in which the p~lshbar 11 is meant to move. An alterna-te position 1~5~
13 is shown for the pushbar 11, reached by pushiny the end of pushbar 11 in a forward and downward direction Referring to Figure 2, the inside oE the housing lO is shown. The pushbar 11 is in a position to press or the forward tongue 18. When it does, the tongue 18 will be forced down by the shape of the housing 10 to contac-t and grip the rim 9 of the push-wheel 8. The push-wheel 8 will then rotate and the main wheel 7 will in turn rotate, thereby propelling the wheelchair. There are ball bearings 19 that allow the housing 10 to sli~e along the rim 9. A
spring 20 on the end of the tongue 18 lifts it off the rim 9 in the absence of a contrary force from the pushbar 11. A
flange 21 on the housing engages a corresponding, retractable cog 22 of the pushbar 11, in order to preven-t the pushbar 11 from driving the reverse tongue 23 on a back stroke by the occupant. By means of a lever or cable, the cog 22 can be retracted and released on the other side of the flange 21, in order to enable a reverse propell;ng motion to be imparted -to the wheelchair.
Referring to Figure 3, a cross-section shows the pushbar 11 with a handle 26, the angle of which can be adjusted for the comfort of the user by means of a hinge and tightening knob 27. The pushbar 11 enters the housing 10, which is slidably attached to the rim 9 of -the push-wheel by means of its shape and its ball bearings 19. A brake pad 28 is mounted on the pushbar 11, which has enough sideward play to allow the occupant to pivot the pushbar 11 toward the wheelchair body, thereby making the brake pad 28 contac-t the trac-tion rim of the main wheel 7. The over-travel guard 12 is attached -to ~Z5,~3~
the armrest 3, but it could alternatively be attached to another part of the Erame 29 of the wheelchair.
Referring -to Figure 4, a top view shows the housing 10, attached to the rim 9 of the push-wheel. The pushbar 11 and its handle 26 ex-tends Erom the housing to where the occupant can grip -the handle 26. The over-travel guard 12 prevents the pushbar 11 and housing assembly from rotating too far around the push-wheel. If the guard 12 were not there, the assembly could travel past -the point at which the occupant could grip the pushbar 11, and could even hit the ground.
The guard 12 is at-tached to the armrest 3. The back 2 and the seat 4 of the wheelchair are also shown.
Referring to Figure ~, an alternative means of switching between forward and reverse directions for the wheelchair is depicted. When the block 39 within the pushbar 11 is in the upper position (the position shown), the contact surface 30 will press upon the forward tongue 18, which will be guided by the shape of the inside of the housing 10 to press upon and rotate the rim 9. On the back-stroke, the spring 20 will lift the -tongue 18 off the rim 9 and allow the pushbar and housing assembly to slide on the ball bearings 19 backwards along the rim 9O As the pushbar is being pulled backwards, the block 39 does not engage the reverse tongue 23, because of the presence of the cavity 31. When the block 39 is put into a lower posi-tion by the occupant, hDwever, the surface 33 will engage the reverse tongue, while the cavity 34 will allow the coasting back-stroke without engaging -the forward tongue 18. There is a connector 32 to the pushbutton control means for switching the position of -the block 39. The pushbar is ;~2S~ 5 ro-tatably attached a-t 40 to the side of the housing 10. This attachment can be made to allow some sideways play in the posi-tion oE -the pushbar in order to enable the optional bra~ing movement described below.
Referring to Figure 6, the pushbar 11 is shown with a flange 35 at its end. ~pon a slight pivotting of the pushbar toward the occupant, the flanqe will lift the braking bar 36, making the braking pad 37 contac-t the underside of the rim 3.The braking bar 3~ is held in place by means of a slotted flange 38 on the housing 10 and is re-turned to its non-braking position by means of a spring 39 also mounted on the housing 10.
The within-described invention may be made in a variety of sizes and shapes and with a variety of accessories, For example, the tongues and housing could be shaped such that the tongues gripped the rim along an extended surface, rather than at a relatively sharp end area of the tongue, as shown in the Figures. The invention may be embodied in other specific forms without departing from -the spirit or essential characteristics thereof. The presently disclosed embodimen-t ~s thereEore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range oE e~uivalency of the claims are -thereEore intended to be embraced therein.
Claims (15)
1. A mechanism for propelling a wheelchair, comprised of:
a) a manual pushbar, adapted for gripping by the user's hand at one end and moveably interlocked with a housing at the other end;
b) the said housing, adapted to be slidably attached to the rim of a wheel on a wheelchair and enclosing a moveable tongue;
c) the said tongue, enclosed in the housing and juxtaposed to the pushbar such that pressure on the hand-gripping end of the pushbar in one direction forces the tongue to press upon the wheel;
d) the said tongue being releasable from pressing upon the wheel upon a reverse pressure being applied to the pushbar;
and e) an over-travel guard means to prevent the pushbar from rotating too far around the wheel.
a) a manual pushbar, adapted for gripping by the user's hand at one end and moveably interlocked with a housing at the other end;
b) the said housing, adapted to be slidably attached to the rim of a wheel on a wheelchair and enclosing a moveable tongue;
c) the said tongue, enclosed in the housing and juxtaposed to the pushbar such that pressure on the hand-gripping end of the pushbar in one direction forces the tongue to press upon the wheel;
d) the said tongue being releasable from pressing upon the wheel upon a reverse pressure being applied to the pushbar;
and e) an over-travel guard means to prevent the pushbar from rotating too far around the wheel.
2. A pair of the mechanism of Claim 1, in combination with a wheelchair.
3. The mechanism of Claim 1, with the addition of a reverse power control means, comprised of a second tongue and a retractable cog on the pushbar.
4. The mechanism of Claim 1, with the addition of a reverse power control means, comprised of a second tongue and at least one cavity in the pushbar, into which the end of the tongue can fit.
5. The mechanism of Claims 1, 2, or 3, in which the pushbar powers the wheel by means of a manual, partial rotational forward and backward stroking parallel to the circumference of the wheel.
6. The mechanism of Claims 1, 2, or 3, in which the mechanism is attached to a main traction wheel of a wheelchair.
7. The mechanism of Claims 1, 2, or 3, in which the mechanism is attached to a pushwheel concentric to the main traction wheel of a wheelchair.
8. The mechanism of Claim 1, 2, or 3, in which there are grooves on the rim of the wheel to which the mechanism is attached, and complementary ridges on the tongue.
9. The mechanism of Claims 1, 2, or 3, in which the mechanism is slidably attached to the rim by means of ball bearings.
10. The mechanism of Claims 1, 2, or 3, in which the gripping tongue is held away from the rim of the wheel when not pressed by the pushbar by means of a spring.
11. The mechanism of Claims 1, 2, or 3, in which the mechanism is enclosed in an over-travel guard frame that is affixed to the body of the wheelchair.
12. The mechanism of Claims 1, 2, or 3, in which the mechanism has additionally a braking means.
13. The mechanism of Claims 1, 2, or 3, in which the hand-gripping part of the pushbar is adjustably attached to the main part of the pushbar.
14. The mechanism of Claims 1, 2, or 3, in which each tongue is affixed to the end of a pushbar.
15. The mechanism of Claims 1, or 3, in which the mechanism is sold as a kit with attaching means and instructions that enable the mechanism to be installed on the wheel of a wheelchair.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000539692A CA1252035A (en) | 1987-06-15 | 1987-06-15 | Sliding pushbar mechanism for wheelchair rims |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000539692A CA1252035A (en) | 1987-06-15 | 1987-06-15 | Sliding pushbar mechanism for wheelchair rims |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1252035A true CA1252035A (en) | 1989-04-04 |
Family
ID=4135903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000539692A Expired CA1252035A (en) | 1987-06-15 | 1987-06-15 | Sliding pushbar mechanism for wheelchair rims |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1252035A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU671791B1 (en) * | 1995-11-17 | 1996-09-05 | Nabco Limited | Motor-driven vehicle |
-
1987
- 1987-06-15 CA CA000539692A patent/CA1252035A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU671791B1 (en) * | 1995-11-17 | 1996-09-05 | Nabco Limited | Motor-driven vehicle |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |