CA1253698A - Drive train for self-propelled mowers - Google Patents
Drive train for self-propelled mowersInfo
- Publication number
- CA1253698A CA1253698A CA000443725A CA443725A CA1253698A CA 1253698 A CA1253698 A CA 1253698A CA 000443725 A CA000443725 A CA 000443725A CA 443725 A CA443725 A CA 443725A CA 1253698 A CA1253698 A CA 1253698A
- Authority
- CA
- Canada
- Prior art keywords
- drive
- plates
- engine
- driven
- housing
- 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
The self-propelled rotary lawn mower has rear drive wheels and front support wheels and an engine driving a rotary cutter blade mounted inside the housing. A transmission is mounted on the housing and has an input shaft and an output shaft driven by the engine through a belt drive to the transmission input shaft. The transmission output shaft extends across the mower and has, on each end, a drive gear driving an internal ring gear mounted in the drive wheel. The transmission includes a clutch between the input and output shafts. The clutch has multiple drive and driven plate sets immersed in lubricant, and a control for moving the plate sets into engagement to cause lubricant to be expelled and the plates to lock up to transmit power from the input shaft to the output shaft.
The self-propelled rotary lawn mower has rear drive wheels and front support wheels and an engine driving a rotary cutter blade mounted inside the housing. A transmission is mounted on the housing and has an input shaft and an output shaft driven by the engine through a belt drive to the transmission input shaft. The transmission output shaft extends across the mower and has, on each end, a drive gear driving an internal ring gear mounted in the drive wheel. The transmission includes a clutch between the input and output shafts. The clutch has multiple drive and driven plate sets immersed in lubricant, and a control for moving the plate sets into engagement to cause lubricant to be expelled and the plates to lock up to transmit power from the input shaft to the output shaft.
Description
-` ~.2~
DRIVE TRAIN FOR SELF-PROPELLED MOWERS
FIELD OF THE INVENTION
This invention relates to self-propelled lawn mower driven trains.
BACKGROUND OF THE IN~ENTIO_ When the clutch is engaged on a self-propelled rotary mower the torque typically causes the front wheels to lift off the ground causing a skip in the mowing. If the drive train uses drive rollers on the tires, very careful actuation can permit slippage but from a practical standpoint even that clutch will cause front wheel lift when engaged. Since wheel lift causes a skip in the mowing, the operator learns that he should back up after stopping so as to avoid the skip when restarting. That is a nuisance and it is desirable to avoid wheel lift. Even with a reel-type mower the jump caused by clutch engagement is troublesome and desirably avoided.
Attention is directed to Shaw patent No. 2,947,132, Jones U.S. patent No. 4,117,652 and Wehner U.S. Patent No. 2,860,473.
SUMMARY OF THE INVENTION
The invention provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including clutch means comprising multiple drive and driven plates which are separated when the clutch means is disengaged, means biasing the plates to separated positions, and manual control means actuated by an operator for variably applying axial load to the plates against the action of the biasing means so as to variably engage the clutch means to S
~ ~ ~536~
~ -lA-effect rotation of the drive wheel at selective speeds within a speed range between zero and substantially above zero.
The invention also provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including a worm gear driven by the engine, a worm wheel driven by the worm gear, and clutch means including multiple drive plates driven by the worm gear and multiple driven plates which are operably connected to the drive wheel and which are separated from the drive plates when the clutch means is disengaged, means biasing the plates to non-driving separated positions, and manual control means actuated by an operator for variably applying axial load to the plates against the action of the biasing means so as to continuously variably engage the clutch means to effect rotation of the drive wheel at selective speeds within a speed range between zero and substantially above zero.
The invention also provides a self-propelled rotary lawn mower comprising a housing having rear drive wheels and front support wheels, an engine mounted on the housing, a rotary cutter blade mounted inside the housing and driven by the engine, a transmission mounted on the housing and having an input shaft and an output shaft, a belt drive from the engine to the input shaft, which output shaft extends across the housing and has, on each end, a drive gear, each drive wheel having an internal ring gear engaged by one of the drive gears, which transmission includes clutch means between the input and output shafts, which clutch means includes multiple drive and driven plate sets immersed in lubricant, means biasing the plate sets into non-driving separated positions, and manual ~ontrol ~:25;~6~3 ~ -lB-means actuated by an operator for selectively applying axial load to the plates so as to move the plate sets into engagement against the action of the biasing means to cause lubricant to be expelled from between the plates and so as to effect continuously variable operator controlled rotation of the drive wheels within a speed range from zero to substantially above zero.
The invention also provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including clutch means for varying the rate of rotation of the drive wheel and including multiple drive and driven plates which are separated when the clutch means is disengaged, means biasing the plates to separated positions, and manuaI control means actuated by an operator ~or variably applying an~axial load to the plates against the action of the biasing means so as to va~riably engage the clutch means to effect continuously variable operator controlled rotation of the drive wheel within a speed range from zero t~o substantially above zero.
The invention also provides a self-propelled lawn~mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including a worm gear driven by the engine, a worm wheel driven by the worm gear, and clutch means for selectively varying the amount of power delivered from the engine to the drive wheel and including multi~le drive plates driven by the worm gear and multiple driven plates which are operably connected to the drive wheel and which are ; 35 separated from the drive plates when the clutch means is disengaged, means biasing the plates to non-driving separated positions, and manual control '. '~"
~z53ç;g8 -lC-: means actuated by an operator for variably applying axial load to the plates against the action of the ~ biasing means so as to~variably engage the clutch : means to cause continuously variable operator 5~ controlled rotation of the~drive wheel within a speed :~ range from zero to substantially above zero.
The invention also provides a : self-propelled rotary lawn mower including a housing having front support wheels and rear drive wheels each having an internal ring gear, an engine mounted on the housing,:a rotary cutter blade mounted inside the housing and driven by the engine, and~a drive train for delivering power erom the engine to the drive wheels and including a drive belt driven by the : engine, and a transmission mounted on the housing~and having an input shaft driven by the drive~belt, an output shaft extending across the housing and having, at each end, a dr:ive~ gear~engaged with one of the internal ring gears, a~nd clutch means between the 20 ~: input and output s~hafts for selectively varying the power level transmitted from the engine to the rear : , drive wheels and including multiple drive plates on : the input:~shaft,~multiple drlven plates on the output shaft and:extending intermediate the drive plates, 25 ~: means biasing the plates into non-driving separated :: positions,~and manual control means actuatable by an operator: fo~r~vari:ably applying axial:load to the plates against the action of the biasing means so as to effect continuously variable operator controlled 30~ ~ rotatlon of the drive wheels within a speed range from zero to substantially above zero.
The invention also provides a self-propelled rotary:lawn mower including a housing ;: :~ having front support wheels and rear drive wheels ~ ~ ~ 35 each having an internal ring gear, an engine mounted : on the housing, a rotary cutter blade mounted inside : the housing and driven by the engine, and a drive ~ :, ~ . ~.
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5i369~3 train for delivering power from the engine to the drive wheels and including a drive belt driven by the engine, and a transmission mounted on the housing and having a worm driven by the drive belt, a worm wheel engaged by the worm, an output shaft extending across the housing and having, at each end, a drive gear engaged with one of the internal ring gears, and clutch means between the worm wheel and the output shaft for selectively varying the power level transmitted from the engine to the rear drive wheels and including multiple drive plates on the worm wheel, multiple driven plates on the output shaft and extending intermediate the drive plates, means biasing the plates into non~driving separated positions, and manual control means actuatable by an operator for variably appIying axial load on the plates against the action of the biasing means so as to effect continuously variable operator controlled rotation of the drive wheels within a speed range from zero to substantially above zero.
This invention is not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation showing the general orientation of the drive.
. .
,, , 536g8 Fig. 2 is a fragmentary perspective view showing the drive train to the wheels.
Fig. 3 is a plan view of the clutch control.
Fig. 4 is a vertical section on line 4-4 in Fig. 3.
Fig. 5 is a vertical section on line 5-5 in Fig. 3.
DETAILED DESCRIPTION OF THE DR~WINGS
The lawn mo~er 10 has a housing ~1~
supporting an engine 12 inside the cover 14. The engine drives shaft 16 on which the rotary mower blade 18 i5 moun~ed. The shaft 16 also carries a pulley 20 which drives a drive belt to pulley 22 mounted on input shaft 24 which projects upwardly from the transmission case 26. The lower end of shaft 24 i6 received in beaIing 28 and the hardened steel worm gear 30 engages bron~e worm wheel 32. The upper end of shaft 24 lS journaled in bearing 34.
WOLm wheel 3~ is a spur gear keyed at 36 to drive member 38 which is journaled on the driven shaft 40 which extends transversely of the lawn mower and is provided, on each end, with a gear 42 which engages the internal ring gear 44 carried by each of the eear drive wheels 46 of the mower. The front of the mower housing is supported on front wheels 47.
The drive shaft 40 is jouLnaled in a bearing 48 at one end of the gear case 26 and in bearing 50 at the other end. Both bearings are provided with packing 52 to prevent los~ of lubricant along the sha~t. The worm wheel is selec~ively connected to the drive shaft 40 through a clu~ch.
The clutch includes the axially facing surface 54 of the drive member 38 which functions as - . - :
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a driver plate engageable with the adjacent dLiven plate 56. The clutch includes four additional driven plates 56. All the driven plates are shaped with a configuration such that the driven plates are, in effect, keyed at 57 to the driven sleeve 58. In a similar manner, all of the independent driver plates 50 are keyed at 61 to the driver member 3~. When the clutch is disengaged, there is relative rotation be~ween the driver plates and the driven plates.
When the collar 62 is moved towards the worm wheel, it will squeeæe the plates together so the driver plates engage the driven plates which in turn drive the sleeve 58 which drives the driven shaft 40 through the drive pin 64. A considerable axial load must be applied to the collar 62 to engage the ;~ clutch. The axial load is absorbed by the thrust bearing 66 mounted between the thrust washer 68, 68 on each side of the bearing, the thrust washer adjacent the inner wall of the casing being pushed into engagement with the inside axially facing urface of bearing 50.
; The transmission housing is filled with lubricant. The driver plates and driven plates are hardened carbon steel plates and are not the kind of plates found in a dry clutch. When the clutch is disengaged, lubricant can get between the various plates. When the clutch is engaged, the axial loading first has to squeeze the lubricant out from between the plates in order for the plates to drive and the clutch to become fully opera~ive. Therefore, this clutch with the proper number of plate sets and proper axial loading can be made to engage relatively slowly. This permits the speed of the mower to gradually increase. When the clutch is Eully ```-` ~L25~
engaged, there is no slippage for all practical effects, but during the engagement there i8 slippage and the front wheels will not lift off the ground.
The accelleration is smooth.
S The clutch is actuated ~y means of the shift arm or yoke 70 mounted on and keyed to shaft 72 projecting from the top of the gear case parallel ~o ths worm gear shaft. The lower end of the shaft 72 is journaled in a socket 74 molded into the lower part of the case 26. The shaf~ carries a shif~ing fork 76 having fingers 78 projecting inwardly to engage groove 81 in collar 62. One snd of the yoks 70 has a Bowden wire (a push/pull cable) 81 connected thereto through spring B2. The Bowden wire 80 is anchored in bracket 84 mounted on the top of the transmission housing. A coil spring 86 connected between the bracket 84 and the other end 88 of yoke 70 biases the yoke to the position in which the clutch is disengaged. The Bowden wire is actuated by ~he manual control 89 carried on the handle 90 and having an over center action. The control goes over center and the clutch remains engaged until ~he manual control is actuated to disengage the clutch.
As soon as the manual control is actuated back over center, the re~urn spring 86 will ensure that the collar moves back from the stacked clutch plates and permits them to resume relative rota~ion between the plates.
The reduction in the belt drive from the engine shaft to the WOLm gear is 1.75:1. The reduction at the point of engagement of the drive gears with the internal gears of the drive wheels is 4:1. The worm gearset provides only a 4:1 reduction as opposed to the usual 7:1 reduction necessitated by : . ~
:
~ 2~ 9~
the usual external gear at the wheel providing only
DRIVE TRAIN FOR SELF-PROPELLED MOWERS
FIELD OF THE INVENTION
This invention relates to self-propelled lawn mower driven trains.
BACKGROUND OF THE IN~ENTIO_ When the clutch is engaged on a self-propelled rotary mower the torque typically causes the front wheels to lift off the ground causing a skip in the mowing. If the drive train uses drive rollers on the tires, very careful actuation can permit slippage but from a practical standpoint even that clutch will cause front wheel lift when engaged. Since wheel lift causes a skip in the mowing, the operator learns that he should back up after stopping so as to avoid the skip when restarting. That is a nuisance and it is desirable to avoid wheel lift. Even with a reel-type mower the jump caused by clutch engagement is troublesome and desirably avoided.
Attention is directed to Shaw patent No. 2,947,132, Jones U.S. patent No. 4,117,652 and Wehner U.S. Patent No. 2,860,473.
SUMMARY OF THE INVENTION
The invention provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including clutch means comprising multiple drive and driven plates which are separated when the clutch means is disengaged, means biasing the plates to separated positions, and manual control means actuated by an operator for variably applying axial load to the plates against the action of the biasing means so as to variably engage the clutch means to S
~ ~ ~536~
~ -lA-effect rotation of the drive wheel at selective speeds within a speed range between zero and substantially above zero.
The invention also provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including a worm gear driven by the engine, a worm wheel driven by the worm gear, and clutch means including multiple drive plates driven by the worm gear and multiple driven plates which are operably connected to the drive wheel and which are separated from the drive plates when the clutch means is disengaged, means biasing the plates to non-driving separated positions, and manual control means actuated by an operator for variably applying axial load to the plates against the action of the biasing means so as to continuously variably engage the clutch means to effect rotation of the drive wheel at selective speeds within a speed range between zero and substantially above zero.
The invention also provides a self-propelled rotary lawn mower comprising a housing having rear drive wheels and front support wheels, an engine mounted on the housing, a rotary cutter blade mounted inside the housing and driven by the engine, a transmission mounted on the housing and having an input shaft and an output shaft, a belt drive from the engine to the input shaft, which output shaft extends across the housing and has, on each end, a drive gear, each drive wheel having an internal ring gear engaged by one of the drive gears, which transmission includes clutch means between the input and output shafts, which clutch means includes multiple drive and driven plate sets immersed in lubricant, means biasing the plate sets into non-driving separated positions, and manual ~ontrol ~:25;~6~3 ~ -lB-means actuated by an operator for selectively applying axial load to the plates so as to move the plate sets into engagement against the action of the biasing means to cause lubricant to be expelled from between the plates and so as to effect continuously variable operator controlled rotation of the drive wheels within a speed range from zero to substantially above zero.
The invention also provides a self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including clutch means for varying the rate of rotation of the drive wheel and including multiple drive and driven plates which are separated when the clutch means is disengaged, means biasing the plates to separated positions, and manuaI control means actuated by an operator ~or variably applying an~axial load to the plates against the action of the biasing means so as to va~riably engage the clutch means to effect continuously variable operator controlled rotation of the drive wheel within a speed range from zero t~o substantially above zero.
The invention also provides a self-propelled lawn~mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from the engine to the drive wheel and including a worm gear driven by the engine, a worm wheel driven by the worm gear, and clutch means for selectively varying the amount of power delivered from the engine to the drive wheel and including multi~le drive plates driven by the worm gear and multiple driven plates which are operably connected to the drive wheel and which are ; 35 separated from the drive plates when the clutch means is disengaged, means biasing the plates to non-driving separated positions, and manual control '. '~"
~z53ç;g8 -lC-: means actuated by an operator for variably applying axial load to the plates against the action of the ~ biasing means so as to~variably engage the clutch : means to cause continuously variable operator 5~ controlled rotation of the~drive wheel within a speed :~ range from zero to substantially above zero.
The invention also provides a : self-propelled rotary lawn mower including a housing having front support wheels and rear drive wheels each having an internal ring gear, an engine mounted on the housing,:a rotary cutter blade mounted inside the housing and driven by the engine, and~a drive train for delivering power erom the engine to the drive wheels and including a drive belt driven by the : engine, and a transmission mounted on the housing~and having an input shaft driven by the drive~belt, an output shaft extending across the housing and having, at each end, a dr:ive~ gear~engaged with one of the internal ring gears, a~nd clutch means between the 20 ~: input and output s~hafts for selectively varying the power level transmitted from the engine to the rear : , drive wheels and including multiple drive plates on : the input:~shaft,~multiple drlven plates on the output shaft and:extending intermediate the drive plates, 25 ~: means biasing the plates into non-driving separated :: positions,~and manual control means actuatable by an operator: fo~r~vari:ably applying axial:load to the plates against the action of the biasing means so as to effect continuously variable operator controlled 30~ ~ rotatlon of the drive wheels within a speed range from zero to substantially above zero.
The invention also provides a self-propelled rotary:lawn mower including a housing ;: :~ having front support wheels and rear drive wheels ~ ~ ~ 35 each having an internal ring gear, an engine mounted : on the housing, a rotary cutter blade mounted inside : the housing and driven by the engine, and a drive ~ :, ~ . ~.
: .
` ~ .
, :~. . :: .
5i369~3 train for delivering power from the engine to the drive wheels and including a drive belt driven by the engine, and a transmission mounted on the housing and having a worm driven by the drive belt, a worm wheel engaged by the worm, an output shaft extending across the housing and having, at each end, a drive gear engaged with one of the internal ring gears, and clutch means between the worm wheel and the output shaft for selectively varying the power level transmitted from the engine to the rear drive wheels and including multiple drive plates on the worm wheel, multiple driven plates on the output shaft and extending intermediate the drive plates, means biasing the plates into non~driving separated positions, and manual control means actuatable by an operator for variably appIying axial load on the plates against the action of the biasing means so as to effect continuously variable operator controlled rotation of the drive wheels within a speed range from zero to substantially above zero.
This invention is not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation showing the general orientation of the drive.
. .
,, , 536g8 Fig. 2 is a fragmentary perspective view showing the drive train to the wheels.
Fig. 3 is a plan view of the clutch control.
Fig. 4 is a vertical section on line 4-4 in Fig. 3.
Fig. 5 is a vertical section on line 5-5 in Fig. 3.
DETAILED DESCRIPTION OF THE DR~WINGS
The lawn mo~er 10 has a housing ~1~
supporting an engine 12 inside the cover 14. The engine drives shaft 16 on which the rotary mower blade 18 i5 moun~ed. The shaft 16 also carries a pulley 20 which drives a drive belt to pulley 22 mounted on input shaft 24 which projects upwardly from the transmission case 26. The lower end of shaft 24 i6 received in beaIing 28 and the hardened steel worm gear 30 engages bron~e worm wheel 32. The upper end of shaft 24 lS journaled in bearing 34.
WOLm wheel 3~ is a spur gear keyed at 36 to drive member 38 which is journaled on the driven shaft 40 which extends transversely of the lawn mower and is provided, on each end, with a gear 42 which engages the internal ring gear 44 carried by each of the eear drive wheels 46 of the mower. The front of the mower housing is supported on front wheels 47.
The drive shaft 40 is jouLnaled in a bearing 48 at one end of the gear case 26 and in bearing 50 at the other end. Both bearings are provided with packing 52 to prevent los~ of lubricant along the sha~t. The worm wheel is selec~ively connected to the drive shaft 40 through a clu~ch.
The clutch includes the axially facing surface 54 of the drive member 38 which functions as - . - :
.. : .. ,. -, .,, : ~ , , .25369E~
a driver plate engageable with the adjacent dLiven plate 56. The clutch includes four additional driven plates 56. All the driven plates are shaped with a configuration such that the driven plates are, in effect, keyed at 57 to the driven sleeve 58. In a similar manner, all of the independent driver plates 50 are keyed at 61 to the driver member 3~. When the clutch is disengaged, there is relative rotation be~ween the driver plates and the driven plates.
When the collar 62 is moved towards the worm wheel, it will squeeæe the plates together so the driver plates engage the driven plates which in turn drive the sleeve 58 which drives the driven shaft 40 through the drive pin 64. A considerable axial load must be applied to the collar 62 to engage the ;~ clutch. The axial load is absorbed by the thrust bearing 66 mounted between the thrust washer 68, 68 on each side of the bearing, the thrust washer adjacent the inner wall of the casing being pushed into engagement with the inside axially facing urface of bearing 50.
; The transmission housing is filled with lubricant. The driver plates and driven plates are hardened carbon steel plates and are not the kind of plates found in a dry clutch. When the clutch is disengaged, lubricant can get between the various plates. When the clutch is engaged, the axial loading first has to squeeze the lubricant out from between the plates in order for the plates to drive and the clutch to become fully opera~ive. Therefore, this clutch with the proper number of plate sets and proper axial loading can be made to engage relatively slowly. This permits the speed of the mower to gradually increase. When the clutch is Eully ```-` ~L25~
engaged, there is no slippage for all practical effects, but during the engagement there i8 slippage and the front wheels will not lift off the ground.
The accelleration is smooth.
S The clutch is actuated ~y means of the shift arm or yoke 70 mounted on and keyed to shaft 72 projecting from the top of the gear case parallel ~o ths worm gear shaft. The lower end of the shaft 72 is journaled in a socket 74 molded into the lower part of the case 26. The shaf~ carries a shif~ing fork 76 having fingers 78 projecting inwardly to engage groove 81 in collar 62. One snd of the yoks 70 has a Bowden wire (a push/pull cable) 81 connected thereto through spring B2. The Bowden wire 80 is anchored in bracket 84 mounted on the top of the transmission housing. A coil spring 86 connected between the bracket 84 and the other end 88 of yoke 70 biases the yoke to the position in which the clutch is disengaged. The Bowden wire is actuated by ~he manual control 89 carried on the handle 90 and having an over center action. The control goes over center and the clutch remains engaged until ~he manual control is actuated to disengage the clutch.
As soon as the manual control is actuated back over center, the re~urn spring 86 will ensure that the collar moves back from the stacked clutch plates and permits them to resume relative rota~ion between the plates.
The reduction in the belt drive from the engine shaft to the WOLm gear is 1.75:1. The reduction at the point of engagement of the drive gears with the internal gears of the drive wheels is 4:1. The worm gearset provides only a 4:1 reduction as opposed to the usual 7:1 reduction necessitated by : . ~
:
~ 2~ 9~
the usual external gear at the wheel providing only
2:1 reducti~n.
Due to the 4:1 reduction at the wheels, the present clutch operates at higher speed that the prior design. This has advantages in that the torque handled by the clutch lS much lower and the engagemen~ is smoother (softer), both resulting in less shock to the transmission. Furthermore, the elutch has more positive lock-up when engaged ~due to less torque) and slippage is descreased. The 4:1 reduction in the worm gearset reduces loading which reduces heat generation and reduces the operating temperature of the transmission. The temperature reduction is great enough to permit the transmission I5 gear case to be molded out of plastic as opposed ~o the metal in the prior art. This is a direct cost reduction. The greatly reduced operating temperature results in a very substantial increase in life. The prior art arrangement generated such high temperature~ that it caused considerable wear which in turn caused even higher temperatures and everything worked towards shortening the useful life of the transmission.~
The greatIy improved performance of the gearset by reason of~reducing the gear ratio permits a very substantial increase in life as noted above.
The presen~ clutch arrangement contributes to the ; increased life with its inheren~ slippage on engagement. This avoids the high shock loads found 30 in the art. Therefore, the engagement is easy and avoids the high loads in prior designs.
::
::
~L2536918 . ~
This invention has application to reel-type mowers as well.~ These mowers tend to tilt back on their rolleLs when the clutch engages. The present arrangement should avoid that and allow the mower to accelerate to speed smoothly.
I claim: ~
:::
:: :: :
:
:: :
: ,
Due to the 4:1 reduction at the wheels, the present clutch operates at higher speed that the prior design. This has advantages in that the torque handled by the clutch lS much lower and the engagemen~ is smoother (softer), both resulting in less shock to the transmission. Furthermore, the elutch has more positive lock-up when engaged ~due to less torque) and slippage is descreased. The 4:1 reduction in the worm gearset reduces loading which reduces heat generation and reduces the operating temperature of the transmission. The temperature reduction is great enough to permit the transmission I5 gear case to be molded out of plastic as opposed ~o the metal in the prior art. This is a direct cost reduction. The greatly reduced operating temperature results in a very substantial increase in life. The prior art arrangement generated such high temperature~ that it caused considerable wear which in turn caused even higher temperatures and everything worked towards shortening the useful life of the transmission.~
The greatIy improved performance of the gearset by reason of~reducing the gear ratio permits a very substantial increase in life as noted above.
The presen~ clutch arrangement contributes to the ; increased life with its inheren~ slippage on engagement. This avoids the high shock loads found 30 in the art. Therefore, the engagement is easy and avoids the high loads in prior designs.
::
::
~L2536918 . ~
This invention has application to reel-type mowers as well.~ These mowers tend to tilt back on their rolleLs when the clutch engages. The present arrangement should avoid that and allow the mower to accelerate to speed smoothly.
I claim: ~
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Claims (13)
1. A self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from said engine to said drive wheel and including clutch means comprising multiple drive and driven plates which are separated when said clutch means is disengaged, means biasing said plates to separated positions, and manual control means actuated by an operator for variably applying axial load to said plates against the action of said biasing means so as to variably engage said clutch means to effect rotation of said drive wheel at selective speeds within a speed range between zero and substantially above zero.
2. A lawn mower according to Claim 1 in which said clutch is lubricated and the lubricant is expelled from between said plates as said clutch is engaged.
3. A self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from said engine to said drive wheel and including a worm gear driven by said engine, a worm wheel driven by said worm gear, and clutch means including multiple drive plates driven by said worm gear and multiple driven plates which are operably connected to said drive wheel and which are separated from said drive plates when said clutch means is disengaged, means biasing said plates to non-driving separated positions, and manual control means actuated by an operator for variably applying axial load to said plates against the action of said biasing means so as to continuously variably engage said clutch means to effect rotation of said drive wheel at selective speeds within a speed range between zero and substantially above zero.
4. A lawn mower according to Claim 3 in which said driven plates of said clutch means are drivingly connected to a drive shaft, a drive gear on one end of said drive shaft, and a driven gear mounted on said wheel and driven by said drive gear.
5. A lawn mower according to Claim 4 in which said driven gear is an internal ring gear.
6. A lawn mower according to Claim 5 in which the speed reduction at said wheel is about 4:1.
7. A self-propelled rotary lawn mower comprising a housing having rear drive wheels and front support wheels, an engine mounted on said housing, a rotary cutter blade mounted inside said housing and driven by said engine, a transmission mounted on the housing and having an input shaft and an output shaft, a belt drive from said engine to said input shaft, said output shaft extending across said housing and having, on each end, a drive gear, each drive wheel having an internal ring gear engaged by one of said drive gears, said transmission including clutch means between said input and output shafts, said clutch means including multiple drive and driven plate sets immersed in lubricant, means biasing said plate sets into non-driving separated positions, and manual control means actuated by an operator for selectively applying axial load to said plates so as to move said plate sets into engagement against the action of said biasing means to cause lubricant to be expelled from between said plates and so as to effect continuously variable operator controlled rotation of said drive wheels within a speed range from zero to substantially above zero.
8. A lawn mower according to Claim 7 in which there is a substantial speed reduction at the drive wheels.
9. A lawn mower according to Claim 8 in which said transmission includes a speed reducing worm gearset.
10. A self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from said engine to said drive wheel and including clutch means for varying the rate of rotation of said drive wheel and including multiple drive and driven plates which are separated when said clutch means is disengaged, means biasing said plates to separated positions, and manual control means actuated by an operator for variably applying an axial load to said plates against the action of said biasing means so as to variably engage the clutch means to effect continuously variable operator controlled rotation of said drive wheel within a speed range from zero to substantially above zero.
11. A self-propelled lawn mower having a frame provided with a drive wheel and supporting an engine, a drive train for delivering power from said engine to said drive wheel and including a worm gear driven by said engine, a worm wheel driven by said worm gear, and clutch means for selectively varying the amount of power delivered from said engine to said drive wheel and including multiple drive plates driven by said worm gear and multiple driven plates which are operably connected to said drive wheel and which are separated from said drive plates when said clutch means is disengaged, means biasing said plates to non-driving separated positions, and manual control means actuated by an operator for variably applying axial load to said plates against the action of said biasing means so as to variably engage said clutch means to cause continuously variable operator controlled rotation of said drive wheel within a speed range from zero to substantially above zero.
12. A self-propelled rotary lawn mower including a housing having front support wheels and rear drive wheels each having an internal ring gear, an engine mounted on said housing, a rotary cutter blade mounted inside said housing and driven by said engine, and a drive train for delivering power from said engine to said drive wheels and including a drive belt driven by said engine, and a transmission mounted on said housing and having an input shaft driven by said drive belt, an output shaft extending across said housing and having, at each end, a drive gear engaged with one of said internal ring gears, and clutch means between said input and output shafts for selectively varying the power level transmitted from said engine to said rear drive wheels and including multiple drive plates on said input shaft, multiple driven plates on said output shaft and extending intermediate said drive plates, means biasing said plates into non-driving separated positions, and manual control means actuatable by an operator for variably applying axial load to said plates against the action of said biasing means so as to effect continuously variable operator controlled rotation of said drive wheels within a speed range from zero to substantially above zero.
13. A self-propelled rotary lawn mower including a housing having front support wheels and rear drive wheels each having an internal ring gear, an engine mounted on said housing, a rotary cutter blade mounted inside said housing and driven by said engine, and a drive train for delivering power from said engine to said drive wheels and including a drive belt driven by said engine, and a transmission mounted on said housing and having a worm driven by said drive belt, a worm wheel engaged by said worm, an output shaft extending across said housing and having, at each end, a drive gear engaged with one of said internal ring gears, and clutch means between said worm wheel and said output shaft for selectively varying the power level transmitted from said engine to said rear drive wheels and including multiple drive plates on said worm wheel, multiple driven plates on said output shaft and extending intermediate said drive plates, means biasing said plates into non-driving separated positions, and manual control means actuatable by an operator for variably applying axial load on said plates against the action of said biasing means so as to effect continuously variable operator controlled rotation of said drive wheels within a speed range from zero to substantially above zero.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49096083A | 1983-05-02 | 1983-05-02 | |
| US490,960 | 1995-06-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1253698A true CA1253698A (en) | 1989-05-09 |
Family
ID=23950235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443725A Expired CA1253698A (en) | 1983-05-02 | 1983-12-20 | Drive train for self-propelled mowers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1253698A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11807093B2 (en) | 2020-03-24 | 2023-11-07 | Husqvarna Ab | Drive assembly for lawn care vehicle |
-
1983
- 1983-12-20 CA CA000443725A patent/CA1253698A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11807093B2 (en) | 2020-03-24 | 2023-11-07 | Husqvarna Ab | Drive assembly for lawn care vehicle |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |