CA1164973A - Threshold operation of a vehicle transmission - Google Patents
Threshold operation of a vehicle transmissionInfo
- Publication number
- CA1164973A CA1164973A CA000360094A CA360094A CA1164973A CA 1164973 A CA1164973 A CA 1164973A CA 000360094 A CA000360094 A CA 000360094A CA 360094 A CA360094 A CA 360094A CA 1164973 A CA1164973 A CA 1164973A
- Authority
- CA
- Canada
- Prior art keywords
- output
- engine
- speed
- control means
- transmission
- 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
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2253—Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
- F16H61/465—Automatic regulation in accordance with output requirements for achieving a target input speed
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Control Of Transmission Device (AREA)
- Control Of Fluid Gearings (AREA)
- Operation Control Of Excavators (AREA)
- Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
Abstract
ABSTRACT
A system for controlling a transmission of a vehi-cle dependent upon engine output is disclosed having a sen-sor for sensing the output of the engine of the vehicle, a controller connected to the sensor for controlling the out-put of the transmission of the vehicle dependent upon engine output, and a threshold circuit connected to the controller for inhibiting transmission output until the engine output has attained a predetermined level.
A system for controlling a transmission of a vehi-cle dependent upon engine output is disclosed having a sen-sor for sensing the output of the engine of the vehicle, a controller connected to the sensor for controlling the out-put of the transmission of the vehicle dependent upon engine output, and a threshold circuit connected to the controller for inhibiting transmission output until the engine output has attained a predetermined level.
Description
THRESHOLD OPERAT~ON OF A VEHICLE TRANSMISSION
-BACKGROUND OF TE]E INVENTION
This invention relates to a system for controlling the operation of a vehicle's ~ransmission a~ a threshold level of the vehicle's engine outputO More specifically, the invention relates to a system for delaying the operation of a vehicle's transmission until the engine output speed has attained a predetermined level.
Many modern day vehicles are fully capable of utilizing the vehicle engine for providing both auxiliary ~unctions and vehicle drive. Such vehicles can include, as examples, aerial lift trucks, grade trimmers, fork lif~s, dozers, trenchers and front end loaders. In the control of such vehicles, the operator sets engine speed at a predetermined governed value for powering all functions of the machine~ Thus, when the bucket of a front end loader is to be operated, for example, he levers fo~ controlling the orientation of the bucket are operated and, when the machine is to be driven in the forward ox reverse direction, the forwaxd and reverse drive pedals are opera~ed to in turn operate ~he transmission of the vehicle~ Such an aperation means that when the vehicle is standing still and the bucket is being operated as one of the auxiliary functions of the vehicle, the vehicle's engine is quite likely supplying excessive horsepower and, thereforer consuming excessive fuel.
The present invention instead dr~ves the transmis-sion of the vehicle as a func~ion of engine speed so that a range of engine speed is provided for powering the auxiliary functions of the vehicle before the additional power neces-sary to drive the vehicle is provided. Thus, the present invention allows the engine to run fast enough for supplying _f~ . ~
.
9 ~ 3 the auxiliary functions wi~hout providi.ng transmission output. At higher engine speeds, the transmission output adapts to engine rpm in a load con-trol manner; that is, if the engi.ne speed drops because of excess load, the transmission "downshifts". This "downshift" also occurs as a result of throttle reduction.
SI~MARY OF: TtIF, INVENTION
These advantages are obtained from the present invention in which a sensor senses the output of the engine, a controller which is connected to the sensor controls the transmission output of the vehicle dependent upon the engine output, and a threshold arrangement is connected to the controller for preventing transmission output until the engine output has attained a predetermined level.
More particularly, the present invention provides a system for controlling a transmission of a vehicle dependent upon engine output, said engine being adapted to be driven in a first speed range of operation and also to propel said vehicle by said transmission during a second higher speed range of operation, the transmission having an input connected to an output of the engine and having an output, the system comprising: speed sensing means adapted to sense the output speed of the engine; control :: 20 means connected to said sensing means and adapted to control said transmis-sion output solely dependent upon said engine output; and, threshold means connected to said control means for inhibiting transmission output in the first range of engine operation until said engine output has attained a predetermined reference level, and said control means providing propor-tional control of said transmission relative solely to said engine output speed once said engine output has attained the predetermined reference : level.
BRIEF DESCRIPTI ON OF THE DRAWINGS
These and other features and advantages will become apparent :Erom 3Q a detailed consideration of the invention when taken in conj~mction with the drawings in which:
; 2 .
Figure l shows one type of machine on which the present system can be used;
Figure 2 shows the system according to the present invention; and, Figure 3 is a graph showing swash plate angle of the pump in the hydrostatic transmission shown in Figure 2 as a function of engine output.
DETAILED DESCRIPTION
In Figure l, front end loader lO comprises bucket ll, operator's cab 12 and engine 13. Inside operator's cab 12 are the various levers and pedals for controlling the forward and reverse progress of vehicle lO and the orientation and work performed by bucket ll. Since vehicle lO is of ordinary design, the details of it will not be specifi-~0 ~' -2a-cally shown herein. However, the control system for propelling vehicle lO is shown in detail in Figure 2.
As shown in Figure 2, vehicle lO has its engine 13 controlled by lever 14 (which alternatively may be a foot pedal3 connected to engine 13 by shaft 15. Lever 14 controls the amount of fuel supplied to engine 13 and therefore controls the rotational speed of engine output 160 Output 16 is ~hen connected to hydrostatic transmission 20 in the form of hydraulic pump 21 and hydraulic motor 22 interconnected by hydraulic lines 23 and 24. Hydraulic motor 22 then has an output shaft 25 connected to the drive train of the vehicle for propulsion.
The system according to the present invention for providin~ the operation described herein comprises pulse pickup unit 30 sensing the speed of rotation of disc 31 affixed to engine output 16 and providing a series of output pulses the frequency of which is dependent upon this speed.
Typically, disc 31 has a plur~lity of teeth which interact with a magnetic field established by pulse plckup unit 30 to induce the pulses which are supplied to frequency-to-voltage converter 32. Pulse pickup unit 30 ma~ be an SBlOOA
manufactured by Honeywell Inc. Frequency~to-voltage conver-ter 32 converts the frequency of the pulses received from pulse pickup unit 30 into a voltage proportional to that frequency and supplies that voltage to the positive input of amplifier 33~ The output of ampliier 33 is connected through resistor 34 to one input of summing junction 36.
The function of summing junction 36 and resistor 34 is connected to ground through diode 35 and resistor 41. The other input to summing junction 36 is a reference input which establishes a threshold level below which output shaft 25 of hydros~atic-transmission 20 will not rotate and above~
which the revolutions per minute of output shaft 25 isgoverned by the output o~ engine 130 The output from summing junction 36 is connected to the negative input of amplifier 33~ Frequency-to-voltage converter 32 and ampli~
fier 33 may be a package manufactured by ~oneywell Inc.
under the number W883A. ~esistor 41 and diode 35 are included in the feedback circuit of amplifier 33 for characterizing the output of amplifier 33 as will be discussed with respect to Figure 3.
The output from amplifier 33 is connected through forward/reverse switch 37 the output of which is then connected to valve 38. Yalve 38 may be a V7058A
manufactured by Honeywell Inc. and receives the electrical signal from forward/reverse switch 37 to provide a hydraulic output for controlling the swash plate of pump 21 and, therefore~ the output ~hereof. Forward/reverse switch 37 controls the polarity of the signal supplied to valve 38 for driving vehicle 10 in a forward or a reverse direction.
As described above~ the reference input to summing juncti~n ~6 provides a threshold level for operation of hydrostatic transmission 20. Figure 3 is a graph showing the operation of hydrostatic transmission ~0 as a unction of engine output rpm~ The idle point is the lowest setting of engine 13 providing the lowest output 160 As the engine is throttled upward, output 16 increases and, as a result, ~he pulses from pulse pickup unit 30 increase in frequency.
This increased frequency results in an increased voltage to the positive input of amplifier 33. However, the output from amplifier 33 and forward/reverse switch 37 will not begin to change until the voltage to the positive input of amplifier 33 exceeds the input to the negative input termi-nal which is a function of the reference setting. Once this ._ ~
~1 I ti 4 ~ r7 3 reference setting has been attained by the output from frequency-to-voltage converter 32, the angle of the swash plate of pump 21 will follow curve A of Figure 3 for the forward direction and curve B for the reverse direction.
Curves C and D are provided by the resistor 41 and diode 35 circuit to characterize curves A and B.
It can be seen from Figures 2 and 3 that as the loading on the machine increases, the output 16 of engine 33 reduces which will proportionally reduce the pump swash plate angle and reduce the speed of rotation of output shaft 25 from hydrostatic transmission ~0 resulting in a "downshift". If the forward or reverse progress of vehicle 10 is to be maintained, throttle 14 must be increased to accommodate the increased load up to the point where engine 13 is at its horsepower limit. When vehicle 10 is at a standstill during a time when the~auxiliary functions of the ve~hicle are being utilized, engine speed need only be operated between the idle and the reference point as shown in Figure 3 instead of the higher setting at which present prior art systems are operated. This operation results in an eficient and economical utilization of engine output.
.
' .
-BACKGROUND OF TE]E INVENTION
This invention relates to a system for controlling the operation of a vehicle's ~ransmission a~ a threshold level of the vehicle's engine outputO More specifically, the invention relates to a system for delaying the operation of a vehicle's transmission until the engine output speed has attained a predetermined level.
Many modern day vehicles are fully capable of utilizing the vehicle engine for providing both auxiliary ~unctions and vehicle drive. Such vehicles can include, as examples, aerial lift trucks, grade trimmers, fork lif~s, dozers, trenchers and front end loaders. In the control of such vehicles, the operator sets engine speed at a predetermined governed value for powering all functions of the machine~ Thus, when the bucket of a front end loader is to be operated, for example, he levers fo~ controlling the orientation of the bucket are operated and, when the machine is to be driven in the forward ox reverse direction, the forwaxd and reverse drive pedals are opera~ed to in turn operate ~he transmission of the vehicle~ Such an aperation means that when the vehicle is standing still and the bucket is being operated as one of the auxiliary functions of the vehicle, the vehicle's engine is quite likely supplying excessive horsepower and, thereforer consuming excessive fuel.
The present invention instead dr~ves the transmis-sion of the vehicle as a func~ion of engine speed so that a range of engine speed is provided for powering the auxiliary functions of the vehicle before the additional power neces-sary to drive the vehicle is provided. Thus, the present invention allows the engine to run fast enough for supplying _f~ . ~
.
9 ~ 3 the auxiliary functions wi~hout providi.ng transmission output. At higher engine speeds, the transmission output adapts to engine rpm in a load con-trol manner; that is, if the engi.ne speed drops because of excess load, the transmission "downshifts". This "downshift" also occurs as a result of throttle reduction.
SI~MARY OF: TtIF, INVENTION
These advantages are obtained from the present invention in which a sensor senses the output of the engine, a controller which is connected to the sensor controls the transmission output of the vehicle dependent upon the engine output, and a threshold arrangement is connected to the controller for preventing transmission output until the engine output has attained a predetermined level.
More particularly, the present invention provides a system for controlling a transmission of a vehicle dependent upon engine output, said engine being adapted to be driven in a first speed range of operation and also to propel said vehicle by said transmission during a second higher speed range of operation, the transmission having an input connected to an output of the engine and having an output, the system comprising: speed sensing means adapted to sense the output speed of the engine; control :: 20 means connected to said sensing means and adapted to control said transmis-sion output solely dependent upon said engine output; and, threshold means connected to said control means for inhibiting transmission output in the first range of engine operation until said engine output has attained a predetermined reference level, and said control means providing propor-tional control of said transmission relative solely to said engine output speed once said engine output has attained the predetermined reference : level.
BRIEF DESCRIPTI ON OF THE DRAWINGS
These and other features and advantages will become apparent :Erom 3Q a detailed consideration of the invention when taken in conj~mction with the drawings in which:
; 2 .
Figure l shows one type of machine on which the present system can be used;
Figure 2 shows the system according to the present invention; and, Figure 3 is a graph showing swash plate angle of the pump in the hydrostatic transmission shown in Figure 2 as a function of engine output.
DETAILED DESCRIPTION
In Figure l, front end loader lO comprises bucket ll, operator's cab 12 and engine 13. Inside operator's cab 12 are the various levers and pedals for controlling the forward and reverse progress of vehicle lO and the orientation and work performed by bucket ll. Since vehicle lO is of ordinary design, the details of it will not be specifi-~0 ~' -2a-cally shown herein. However, the control system for propelling vehicle lO is shown in detail in Figure 2.
As shown in Figure 2, vehicle lO has its engine 13 controlled by lever 14 (which alternatively may be a foot pedal3 connected to engine 13 by shaft 15. Lever 14 controls the amount of fuel supplied to engine 13 and therefore controls the rotational speed of engine output 160 Output 16 is ~hen connected to hydrostatic transmission 20 in the form of hydraulic pump 21 and hydraulic motor 22 interconnected by hydraulic lines 23 and 24. Hydraulic motor 22 then has an output shaft 25 connected to the drive train of the vehicle for propulsion.
The system according to the present invention for providin~ the operation described herein comprises pulse pickup unit 30 sensing the speed of rotation of disc 31 affixed to engine output 16 and providing a series of output pulses the frequency of which is dependent upon this speed.
Typically, disc 31 has a plur~lity of teeth which interact with a magnetic field established by pulse plckup unit 30 to induce the pulses which are supplied to frequency-to-voltage converter 32. Pulse pickup unit 30 ma~ be an SBlOOA
manufactured by Honeywell Inc. Frequency~to-voltage conver-ter 32 converts the frequency of the pulses received from pulse pickup unit 30 into a voltage proportional to that frequency and supplies that voltage to the positive input of amplifier 33~ The output of ampliier 33 is connected through resistor 34 to one input of summing junction 36.
The function of summing junction 36 and resistor 34 is connected to ground through diode 35 and resistor 41. The other input to summing junction 36 is a reference input which establishes a threshold level below which output shaft 25 of hydros~atic-transmission 20 will not rotate and above~
which the revolutions per minute of output shaft 25 isgoverned by the output o~ engine 130 The output from summing junction 36 is connected to the negative input of amplifier 33~ Frequency-to-voltage converter 32 and ampli~
fier 33 may be a package manufactured by ~oneywell Inc.
under the number W883A. ~esistor 41 and diode 35 are included in the feedback circuit of amplifier 33 for characterizing the output of amplifier 33 as will be discussed with respect to Figure 3.
The output from amplifier 33 is connected through forward/reverse switch 37 the output of which is then connected to valve 38. Yalve 38 may be a V7058A
manufactured by Honeywell Inc. and receives the electrical signal from forward/reverse switch 37 to provide a hydraulic output for controlling the swash plate of pump 21 and, therefore~ the output ~hereof. Forward/reverse switch 37 controls the polarity of the signal supplied to valve 38 for driving vehicle 10 in a forward or a reverse direction.
As described above~ the reference input to summing juncti~n ~6 provides a threshold level for operation of hydrostatic transmission 20. Figure 3 is a graph showing the operation of hydrostatic transmission ~0 as a unction of engine output rpm~ The idle point is the lowest setting of engine 13 providing the lowest output 160 As the engine is throttled upward, output 16 increases and, as a result, ~he pulses from pulse pickup unit 30 increase in frequency.
This increased frequency results in an increased voltage to the positive input of amplifier 33. However, the output from amplifier 33 and forward/reverse switch 37 will not begin to change until the voltage to the positive input of amplifier 33 exceeds the input to the negative input termi-nal which is a function of the reference setting. Once this ._ ~
~1 I ti 4 ~ r7 3 reference setting has been attained by the output from frequency-to-voltage converter 32, the angle of the swash plate of pump 21 will follow curve A of Figure 3 for the forward direction and curve B for the reverse direction.
Curves C and D are provided by the resistor 41 and diode 35 circuit to characterize curves A and B.
It can be seen from Figures 2 and 3 that as the loading on the machine increases, the output 16 of engine 33 reduces which will proportionally reduce the pump swash plate angle and reduce the speed of rotation of output shaft 25 from hydrostatic transmission ~0 resulting in a "downshift". If the forward or reverse progress of vehicle 10 is to be maintained, throttle 14 must be increased to accommodate the increased load up to the point where engine 13 is at its horsepower limit. When vehicle 10 is at a standstill during a time when the~auxiliary functions of the ve~hicle are being utilized, engine speed need only be operated between the idle and the reference point as shown in Figure 3 instead of the higher setting at which present prior art systems are operated. This operation results in an eficient and economical utilization of engine output.
.
' .
Claims (17)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A system for controlling a transmission of a vehicle dependent upon engine output, said engine being adapted to be driven in a first speed range of operation and also to propel said vehicle by said transmission during a second higher speed range of operation, the transmission having an input connected to an output of the engine and having an output, the system com-prising: speed sensing means adapted to sense the output speed of the engine;
control means connected to said sensing means and adapted to control said transmission output solely dependent upon said engine output; and, thres-hold means connected to said control means for inhibiting transmission out- `
put in the first range of engine operation until said engine output has attained a predetermined reference level, and said control means providing proportional control of said transmission relative solely to said engine output speed once said engine output has attained the predetermined reference level.
control means connected to said sensing means and adapted to control said transmission output solely dependent upon said engine output; and, thres-hold means connected to said control means for inhibiting transmission out- `
put in the first range of engine operation until said engine output has attained a predetermined reference level, and said control means providing proportional control of said transmission relative solely to said engine output speed once said engine output has attained the predetermined reference level.
2. The system of claim 1 wherein said speed sensing means comprises a pulse pickup unit adapted to be associated with said engine output for providing an output signal having a frequency dependent upon engine output speed.
3. The system of claim 2 wherein said sensing means further comprises a frequency-to-voltage converter for receiving said signal from said pulse pickup unit and for providing a voltage output dependent upon said frequency.
4. The system of claim 3 wherein said control means comprises an amplifier having a first input connected to said frequency-to-voltage converter for receiving said voltage output thereof.
5. The system of claim 4 wherein said threshold means comprises a reference means connected to a second input of said amplifier.
6. The system of claim 5 wherein said control means further comprises a forward/reverse circuit connected to an output of said amplifier for determining the forward and reverse direction of travel for said vehicle.
7. A system for controlling a hydrostatic transmission of a vehicle solely dependent upon engine speed, said engine being adapted to be driven in a first speed range of operation and also to propel said vehicle by said transmission during a second higher speed range of operation, the hydro-static transmission including a pump connected to an output of the engine and a hydraulic motor for receiving hydraulic fluid from the pump, the hydraulic motor having an output, the system comprising: speed sensing means adapted to sense the speed of the output of said engine; control means connected to said speed sensing means and adapted to control the flow of hydraulic fluid from said pump to said hydraulic motor solely dependent upon engine speed; and, threshold means connected to said control means for preventing the flow of hydraulic fluid from said pump to said hydraulic motor in the first range of engine operation until the speed of said engine output has attained a predetermined reference level, and said control means providing proportional control of said transmission relative solely to said engine output speed once said engine output has attained the predeter-mined reference level.
8. The system of claim 7 wherein said speed sensing means comprises a pulse pickup unit adapted to provide an output signal having a frequency dependent upon said engine speed.
9. The system of claim 8 wherein said speed sensing means further com-prises a frequency-to-voltage converter connected to said pulse pickup unit for providing a voltage output signal having a voltage dependent upon said frequency.
10. The system of claim 9 wherein said control means comprises a valve adapted to control a swash plate of said pump and means connecting said valve to said frequency-to-voltage converter for controlling said hydraulic motor output as a function of engine speed.
11. The system of claim 9 wherein said control means comprises an amplifier having a first input connected to said frequency-to-voltage converter for receiving said voltage output signal.
12. The system of claim 11 wherein said threshold means comprises reference means connected to a second input of said amplifier for establis-hing a threshold level of engine speed above which said hydrostatic trans-mission is operated and below which said hydrostatic transmission is not operated.
13. The system of claim 12 wherein said control means further comprises a forward/reverse circuit connected to an output of said amplifier for determining the forward and reverse direction of said vehicle.
14. The system of claim 13 wherein said control means further comprises a valve connected to said forward/reverse circuit and adapted to control the swash plate of said pump to control the flow of hydraulic fluid from said pump to said hydraulic motor.
15. The system of claim 7 wherein said control means comprises a valve adapted to control a swash plate of said pump and means connecting said valve to said control means for controlling said hydraulic motor output as a fun-ction of engine speed.
16. The system of claim 5 wherein said control means comprises an amplifier having a first input connected to said speed sensing means.
17. The system of claim 16 wherein said control means further comprises a forward/reverse circuit connected to an output of said amplifier for determining the forward and reverse direction of said vehicle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10396479A | 1979-12-17 | 1979-12-17 | |
| US103,964 | 1979-12-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1164973A true CA1164973A (en) | 1984-04-03 |
Family
ID=22297951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000360094A Expired CA1164973A (en) | 1979-12-17 | 1980-09-11 | Threshold operation of a vehicle transmission |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1164973A (en) |
| DE (1) | DE3047025A1 (en) |
| FR (1) | FR2471879A1 (en) |
| GB (1) | GB2065837B (en) |
| SE (1) | SE8007068L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8501205D0 (en) * | 1985-01-17 | 1985-02-20 | Peritate Ltd | Slave unit |
| DE3632960A1 (en) * | 1986-09-27 | 1988-04-07 | Daimler Benz Ag | Control device for a drive assembly, comprising an engine and an automatic transmission, used to drive a motor vehicle |
| DE3706117A1 (en) * | 1987-02-25 | 1988-09-08 | Linde Ag | CONTROL AND REGULATION DEVICE FOR A DRIVE UNIT |
| DE59801526D1 (en) * | 1998-06-25 | 2001-10-25 | Zahnradfabrik Friedrichshafen | Method for controlling a vehicle drive unit with a continuously variable transmission |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3182444A (en) * | 1963-06-25 | 1965-05-11 | Yale & Towne Inc | Hydraulic drive for industrial truck |
| CA976841A (en) * | 1972-03-23 | 1975-10-28 | Caterpillar Tractor Co. | Override control system for a controlled slippable clutch |
| DE2357283A1 (en) * | 1973-11-16 | 1975-05-28 | Kloeckner Humboldt Deutz Ag | CONTROL DEVICE FOR A DRIVE UNIT FORMED FROM A COMBUSTION ENGINE AND A HYDROSTATIC TRANSMISSION |
-
1980
- 1980-09-11 CA CA000360094A patent/CA1164973A/en not_active Expired
- 1980-10-09 SE SE8007068A patent/SE8007068L/en not_active Application Discontinuation
- 1980-12-10 GB GB8039619A patent/GB2065837B/en not_active Expired
- 1980-12-13 DE DE19803047025 patent/DE3047025A1/en not_active Withdrawn
- 1980-12-15 FR FR8026602A patent/FR2471879A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2065837B (en) | 1983-11-30 |
| SE8007068L (en) | 1981-06-18 |
| DE3047025A1 (en) | 1981-08-27 |
| FR2471879A1 (en) | 1981-06-26 |
| GB2065837A (en) | 1981-07-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |