Abstract: Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission operating method includes asynchronously shifting between a first pair of drive ranges in the transmission via operation of two clutches and a variable displacement hydraulic pump in a hydrostatic assembly. In the method, asynchronously shifting between the two drive ranges includes a plurality of phases that include a swiveling phase where a speed of the hydrostatic assembly is inverted.

Abstract: A work vehicle includes a hydrostatic stepless speed changer device configured to speed-change driving power of an engine steplessly, a plurality of planetary gear speed changer devices configured to speed-change the driving power speed-changed by the stepless speed changer device, a plurality of clutch mechanisms corresponding to the plurality of planetary gear speed changer devices in order to take off the driving powers from these plurality of planetary gear speed changer devices individually, and a traveling speed changer device for speed-changing and transmitting the driving powers transmitted from the plurality of clutch mechanisms to a traveling mechanism. The plurality of planetary gear speed changer devices the plurality of clutch mechanisms and the traveling speed changer device are accommodated in a transmission case.

Abstract: A power split and creep drive system for street sweeper or like specialty vehicle having a single engine is disclosed. The system intends to retrofit and convert on-highway truck chassis into specialty vehicles capable of performing work function and moving at creeping speed, such as a street sweeper. It includes a hydraulic work circuit or power-take-off (PTO) port, a planetary gear set, a hydraulic system comprising pumps and motors to drive the working devices and balance the demand between propulsion and work function such as sweeping. The planetary gear set includes an input shaft connecting to a transmission output shaft of the chassis, a first output shaft connecting to a hydraulic machine, and a second output shaft to vehicle propulsion drive shaft.

Abstract: A shift power transmission apparatus of a tractor that has a small up-down width or a small transverse width and a short front-rear length. A shift output unit is located further toward a vehicle rear side than a combined planetary power transmission unit. A planetary unit output axis and a shift unit input axis are coaxial with each other.

Abstract: A transmission system for a machine is coupled to an engine of the machine that is adapted to generate power. The transmission system includes a hydraulic power path including a variator coupled to the engine. The transmission system also includes a mechanical power path. The mechanical power path includes a first gear arrangement including a plurality of gears. The mechanical power path also includes a second gear arrangement including a plurality of gears. The second gear arrangement is coupled with the first gear arrangement to receive the variable rotational power from the first gear arrangement. The mechanical power path further includes a first clutch assembly and a second clutch assembly. Further, the second gear arrangement directs the variable rotational power received from the first gear arrangement towards a final output member of the machine in a selected direction.

Abstract: A continuously variable power-split transmission with at least four driving ranges, within which the gear ratio of the power-split transmission can be continuously varied by a variator. A first planetary gearset with a plurality of shafts can be connected via shifting elements with another planetary gearset that also has a plurality of shafts and can be connected with a transmission output shaft. The first planetary gearset comprises four shafts and can be connected, via a first shaft, with a transmission input shaft and a first shaft of the variator. Furthermore, the first planetary gearset is connected, via a second shaft, to a second shaft of the variator, and the first planetary gearset is coupled, via a third shaft, to halves of two shifting elements and, via a fourth shaft, the first planetary gearset is coupled to a shifting element half of a further shifting element.

Abstract: A power-split transmission (28) with a first power path and a second power path. In this case, the first power path is a mechanical power path and includes a primary planetary gearset (P1), a secondary planetary gearset (P2) and a tertiary planetary gearset (P3). Furthermore, the power-split transmission (28) is equipped with at least four shifting elements. In addition, a method for operating such a power-split transmission (28) is disclosed. Moreover, a drive-train (10) of a working machine with a power-split transmission (28) of the type concerned is presented.

Abstract: A transmission apparatus includes a planetary gear mechanism, a first path, a second path, and a continuously variable transmission. The planetary gear mechanism has a first gear, a second gear, and a third gear. The first path is configured to transmit power from an output shaft of an engine to the first gear. The second path is configured to transmit the power from the output shaft to the second gear. The continuously variable transmission is disposed in the first path.

Abstract: High efficiency work vehicle drivetrains containing variator assemblies are provided. In one embodiment, the work vehicle drivetrain includes an engine, a variator assembly, and an auxiliary power takeoff (PTO) shaft, which is coupled to the engine and rotatable about a primary power path axis when driven by the engine. The variator assembly includes, in turn, a variator motor and a variator gearbox. The variator gearbox contains a planetary gear system, which is coupled to the variator motor and to the auxiliary PTO shaft. The planetary gear system is rotatable about a planetary axis substantially parallel and offset from the primary power path axis.

Abstract: A spur-gear planetary gearbox with multiple ratios has a spur-gear gearbox with at least one first idler gear arranged concentrically to a spur-gear shaft, and a spur gear connected to this spur-gear shaft, a planetary gear mechanism with a first planetary gear set and a second planetary gear set and a planetary gear shaft rotatable about a planetary gear mechanism axis. One of the planetary gear sets is arranged concentrically to the planetary gear mechanism axis. A first planetary gear and a second planetary gear arranged concentrically to the planetary gear mechanism axis. A gear box and a plurality of speed changing devices are provided, wherein the first idler gear meshes with the first planetary gear, and the spur gear meshes with the second planetary gear. The planetary gearbox is characterized in that a second idler gear is arranged on the spur-gear shaft and can be selectively connected thereto in a torque-transmitting manner.

Abstract: A power train and related vehicle are described for multi-mode power transmission. A first continuously variable power source (“CVP”) may convert rotational power received by the engine for transmission to a second CVP. A variator assembly may receive rotational power from the second CVP at a first input and directly from the engine at a second input. A control assembly may include one or more output components and a plurality of clutch devices arranged between the one or more output components and the variator assembly and engine. In a first state of the control assembly, the plurality of clutch devices may collectively provide direct power transmission between the engine and the one or more output components. In a second state of the control assembly, the plurality of clutches may collectively provide power transmission between the variator and the one or more output components.

Abstract: A system for operating a work vehicle may include an engine and a transmission coupled to the engine. The transmission may include a planetary gear unit configured to be selectively coupled to the engine by engaging one of two directional clutches of the transmission. The transmission may also include a hydrostatic drive unit having an input configured to be rotationally coupled to the engine and an output configured to be rotationally coupled to the planetary gear unit. Moreover, the transmission may include a bypass shaft assembly having a bypass shaft configured to be selectively coupled between the output of the hydrostatic drive unit and a given range clutch of the transmission via a bypass clutch. In addition, the system may include a controller configured to operate the transmission in a hydrostatic bypass mode by disengaging the directional clutches and by engaging the bypass clutch and the given range clutch.

Abstract: The present invention provides an infinitely variable transmission for a powered vehicle which includes a power source. The transmission includes an input shaft and an output shaft, the output shaft being spaced from the input shaft. The transmission further includes a variator coupled between the input shaft and output shaft. In addition, at least two planetary gearsets are disposed adjacent to the variator and an input coupler is configured to selectively couple the variator to the power source.

Abstract: A power split transmission (LG) of vehicle a traction drive (F) includes a continuously variable transmission (G) and a summing transmission (SG). The continuously variable transmission (G) has a primary unit (P) and a secondary unit (S) driven by the primary unit (P). The primary unit (P) has a driveshaft (TW1) connected, directly and without the interposition of a clutch device, with the sun gear (SR) of the summing transmission (SG). The secondary unit (S) has a driveshaft (TW2) connected, without the interposition of a clutch device, with a ring gear (HR) or a planetary carrier (PT) of the summing transmission (SG). The planetary carrier (PT) or the ring gear (HR) of the summing transmission (SG) form an output element of the summing transmission (SG), which is in a driving connection with the wheel drive.

Abstract: The present invention provides a motor vehicle having driver-selectable first and second modes (eco, dynamic) of operation and driver-operable means for selecting the first and second modes. Driver selection of the second mode (dynamic) when the first mode (eco) has also been selected causes the vehicle to deselect the first mode (eco), subsequent deselection by the driver of the second mode (dynamic) causing the first mode (eco) to be reselected automatically by the vehicle. If the first mode (eco) is selected by the driver when the vehicle is in the second mode (dynamic), the vehicle selects the first mode (eco) in addition to the second mode (dynamic). A further aspect is directed to a method.

Abstract: A method for controlling an automated clutch, which comprises a hydraulic clutch actuating system having a hydrostatic actuator, the pressure of which is detected. The method includes using the pressure of the hydrostatic actuator to adapt the characteristic curve of the clutch.

Abstract: A control system has a startup start device that generates and outputs a startup start signal that starts a startup of a vehicle based on an operation of starting up the vehicle, a power supply device that supplies power to each unit of the vehicle, a central control unit that generates and outputs to a motor device for driving the vehicle, a startup command signal that starts up the motor device based on the startup start signal, a startup control unit that performs a startup control of the motor device based on the startup command signal, a drive control unit that performs a drive control of a peripheral device configuring the vehicle, a storage unit that stores first data containing initial information of the peripheral device or setting information set in advance, and a data storage control unit that performs the startup control of the motor device by the startup control unit after storing second data indicating, when the operation of starting up the vehicle is performed, a state of the peripheral device

Abstract: The invention essentially relates to a method for blocking wheels of a vehicle when stopped in which a transmission device (1) is placed between an output (2) of a heat engine (3) and a wheel (5) axle shaft (4). This device (1) comprises an input shaft (13) connected to the output (2) of the engine (3), an output shaft (31) connected to the wheel axle shaft (4), and at least one electrical machine (6, 7). The device also comprises a mechanical assembly (12) interconnecting the input shaft (13), the output shaft (31) and the shaft (8, 9) of the machine. This assembly (12) is connected to a bridge (15) that, in turn, is connected to the wheel (5) axle shaft (4). The invention provides that, in order to block the wheels when the vehicle is stopped and to limit an observable torque on the elements of the assembly (12), the wheel axle shaft is blocked by the mechanical assembly.

Abstract: A hydromechanical powertrain for a ground vehicle. The powertrain, more specifically a transmission, includes an input shaft that is coupled to a rotational power source and an output shaft that is coupled to a load. A first hydrostatic unit coupled to a first gear, while a second hydrostatic unit is selectively coupled to one of a pair of clutches. The first of the clutches has a first clutch gear that is selectably coupled to a first mode gear, which is in turn rotationally fixed to the output shaft. The second of clutches has a second clutch gear that is selectively coupled to a second mode gear, which is in turn rotationally fixed to the input shaft. Also coupled to the input shaft is a planetary gear set.

Abstract: Disclosed is a power-branched transmission, particularly for agricultural vehicles such as tractors or similar, having a stepped planetary gear which is disposed between an input shaft and an output shaft and is used for dividing the power supplied at the input shaft onto a mechanical power branch and a hydraulic power branch. The hydraulic power branch is formed by two hydraulically interconnected, identical hydrostatic axial piston engines which can be selectively operated as a pump or an engine, can be swiveled within a predefined pivoting angle, and can be connected to the input shaft or the stepped planetary gear in a different manner via two respective clutches so as to cover different operating ranges or running steps. In order to obtain better efficiency in such a power-branched transmission, the two hydrostatic axial piston engines are configured as wide-angle hydrostats that are provided with a minimum pivoting angle range of 45°.

Abstract: In a drive train for a motor vehicle provided with an internal combustion engine, an electric drive assembly and a transmission having a compact structural design and including at least six forward speeds, the transmission comprises an input-side planetary gear set and an output side Ravigneaux planetary gear, a sun wheel of the input side planetary gear set is fixed and the six forward gears and one reverse gear are adjustable by closing and opening, in pairs, various clutches and brakes.

Abstract: Automated multi-stage gearbox, includes a basic gearbox with a number of gears and a two-stage split gearing coupled in front of and in series with the basic gearbox. Shifting is effected by compressed-air cylinders which are controlled by a control computer (45) which is programmed to put the split gearing in a neutral position in the event of an input signal representing zero throttle.

Abstract: A continuously variable hydro-mechanical transmission. The transmission includes a transmission housing and a hydrostatic power unit associated with the housing. The hydrostatic power unit includes a pump coupled to a motor with the hydrostatic power unit coupled to a first input shaft and a first output shaft. The hydrostatic power unit is selectively coupled to a synchronous lockup clutch with the first output shaft, wherein a hydrostatic input speed range is selected. A compound planetary gear unit is mounted in the housing with the compound planetary gear unit including a second input shaft, a third input shaft, a fourth input shaft and a second output shaft. The compound planetary gear unit is selectively coupled to the load, selectively coupled to the hydrostatic power unit and coupled to the power source.

Abstract: A hydro-mechanical transmission having a planetary system with three planetary gear sets including a reversing planetary gear set together with two clutches and a reverse brake to provide an infinitely adjustable speed change over the speed range from −20 kph to 60 kph without an additional direction change gear set. The transmission has two forward speed ranges and one reverse speed range. The planetary system has fixed mechanical and hydrostatic power input elements and a fixed output element. The low and high range clutches and the reverse brake direct power flow through the transmission along different paths to produce the different gear ratios. Transmission efficiency is maximized at the field use speed and the transport road speed where an agricultural tractor is most often operated.

Abstract: A hydro-mechanical transmission (2) with a simple construction and which can make full use of its advantages is provided. In a hydro-mechanical transmission in which a hydraulic power transmitting mechanism (10), having a hydraulic pump and a hydraulic motor, and a mechanical power transmitting mechanism (20), using gears, are switchably provided; the speed of input rotation is changed, and the resultant rotation is generated; the mechanical power transmitting mechanism has at least one planetary gear mechanism, and an output shaft (24) of the mechanical power transmitting mechanism is provided so that its output can be generated directly to the outside. The hydraulic pump (11) and the hydraulic motor (12) of the hydraulic power transmitting mechanism are of a variable displacement type. A directly-coupled clutch (30) is interposed between a motor output shaft (14) of the hydraulic power transmitting mechanism and the output shaft of the mechanical power transmitting mechanism.

Abstract: A power distribution transmission is provided with one mechanical and one hydrostatic power branch mounted in a transmission housing (46) driven via a common drive shaft (1) and accumulated in a coupling gear (5). The coupling gear (5), with its several planet gear sets (9, 10, 22, 41) and couplings (27, 32, 35, 39), is connected to an output shaft (53). The coupling gear (5) is mounted on the drive shaft (1). The last planet gear set (41) of the coupling gear (5) can be connected to forward and reverse couplings (K.sub.v and K.sub.r, respectively) and the couplings K.sub.v and K.sub.r can be connected to the output shaft (53).

Abstract: A mechanical transmission (3; MT) is interposed between an input shaft (1) and an output shaft (2), and a hydrostatic transmission (4; HST) is disposed in parallel with the MT (3). Between the input shaft (1) and the input side of the MT, a third planetary gear set (15) is interposed for reducing input shaft rpm to reduced rpm corresponding to a predetermined reduction gear ratio. A fourth selectively-engageable clutch (13) for applying rotation at the reduced rpm in low to intermediate change gear ratio ranges and a fifth selectively-engageable clutch (14) for applying rotation at the input shaft rpm in a high change gear ratio range are provided, so that the number of modes of operation is increased.

Abstract: Described is a method of controlling a power distribution hydromechanical branched transmission consisting of an adjustable hydrostatic unit (4), an integrating planetary gear (10) with at least two outputs (26, 27) and, connected to the integrating planetary gear, a range-changing gear (11) designed as a double planetary gear. The two outputs (26, 27) are connected to the range-changing gear (11) by a first clutch (K1) or a second clutch (K2), and one element of the range-changing gear (11) is controlled by a third clutch (KV). Additional clutches (K3, K4) are fitted for the other ranges. In conditions in which the gear-change position is uncertain, the first clutch (K1) or the second clutch (K2), depending on the instantaneous speed of the vehicle, is synchronized and engaged by adjusting the hydrostatic unit (4), and then either one of the other clutches (K3, K4) or the third clutch (KV) is synchronized and engaged.

Abstract: A multi-range, synchronous shifting, hydromechanical transmission according to the present invention is suitable for application in an automotive drivetrain including a high speed engine. The transmission receives split power inputs from the engine; one input being geared down to a suitable lower speed for driving a continuously variable hydrostatic transmission unit, while the other input drives a counter shaft from which mechanical outputs are take at different speed ratios. A planetary gear set, driven by the hydrostatic transmission unit output, is shiftable to provide either a narrow continuously variable speed hydrostatic output, range suitable for transmission operation in low output ranges or a wide continuously variable speed hydrostatic output range suitable for transmission operation in high output ranges.

Abstract: A continuously variable transmission for vehicles, in which the power from a prime mover is divided by a power dividing mechanism and transmitted to a hydraulic continuously variable transmission (HCVT) apparatus and to a mechanical transmitting means for mechanical transmission of power, and the power from the HCVT apparatus and the mechanical transmitting means is collected and selectively outputted for satisfying both the maximum speed performance and the fuel consumption performance of the vehicle. A lock-up brake in the power dividing mechanism stops the rotation of the hydraulic pump of the HCVT so that the power from the input member may be mechanically transmitted to the mechanical transmitting means only via the power dividing mechanism to achieve a minimum gear ratio.

Abstract: A hydrostatic/mechanical branch power split transmission for power vehicles is disclosed. The transmission includes an infinitely variable hydrostatic converter having a first hydrostatic unit of adjustable volume and a second hydrostatic unit. The transmission also includes a power distribution system whereby the driving power is split into a hydraulic and a mechanical branch and is summed again before the transmission output. The transmission permits various driving strategies or driving programs which can be conveniently adjusted and accessed. There is also a hydrostatic connection which can be switched at several gear racial points. The breaking capacity of the engine and the maximum breaking effect through continuous hydrostatic converter can be utilized and easily controlled. A further variant also enables breaking energy to be recuperated with the hydrostatic converter. The continuous converter can be precisely adjusted to optimize gear shift range selection.

Abstract: An infinitely variable drive transmission including an input member, a summing gear set, and a variable speed transmission having an input element drivable by the input member and an output element, the output element of the variable speed transmission being connectable to one element of the summing gear set, to provide a first path between the input member and the summing gear set. The input member being connectable to another element of the summing gear set to provide a second path between the input member and the summing gear set. The summing gear set includes a driven member drivable by at least one further element of the summing gear set and drive transmitting means connectable between the output element of the variable speed transmission and the other element of the summing gear set.

Abstract: A hydromechanical transmission receives split power inputs from a vehicle engine, one split input driving a hydrostatic power unit and the other split input driving a mechanical power input. The infinitely variable hydrostatic power output is combined in the mechanical power unit with multiple ratios of its split input power to achieve multiple ratios of hydromechanical output power for smoothly propelling a vehicle from rest through multiple transmission ranges to maximum speed, with synchronous shifting between ranges. The hydromechanical transmission is particularly applicable to off-road vehicles, such as agricultural tractors.

Abstract: A hydromechanical transmission receives split power inputs from a vehicle engine, one split input driving a hydrostatic power unit and the other split input driving a mechanical power input. The infinitely variable hydrostatic power output is combined in the mechanical power unit with multiple ratios of its split input power to achieve multiple ratios of hydromechanical output power for smoothly propelling a vehicle from rest through multiple transmission ranges to maximum speed, with synchronous shifting between ranges.

Abstract: A hydrostatic/mechanical branch power split transmission for power vehicles is disclosed. The transmission includes an infinitely variable hydrostatic converter having a first hydrostatic unit of adjustable volume and a second hydrostatic unit. The transmission also includes a power distribution system whereby the driving power is split into a hydraulic and a mechanical branch and is summed again before the transmission output. The transmission permits various driving strategies or driving programs which can be conveniently adjusted and accessed. There is also a hydrostatic connection which can be switched at several gear ratio points. The braking capacity of the engine and maximum braking effect through the continuous hydrostatic converter can be utilized and easily controlled. A further variant also enables braking energy to be recuperated with the hydrostatic converter. The continuous converter can be precisely adjusted to optimize gear shift range selection.

Abstract: A split torque transmission includes a hydrostatic transmission and a mechanical transmission both being driven by an engine. The output of the hydrostatic transmission and the mechanical transmission are both selectively coupled to a machine through a final output shaft. The mechanical transmission incudes a full range high forward and reverse mechanism selectively coupled to a planetary arrangement. The planetary arrangement sums the speed of the hydrostatic transmission with the full range high forward and reverse mechanism. This arrangement provides a smooth and continuous change in the speed of the machine in both the forward and reverse directions throughout its entire speed range which is identical in both directions of travel.

Abstract: A control system in which a judgment is made such that (i) a vehicle is in a forward drive control state, on condition that the forward/reverse drive lever is placed in the forward drive position and the actual speed ratio exceeds a specified small value in a forward drive direction, (ii) the vehicle is in a reverse drive control state on condition that the lever is placed in the reverse drive position and the actual speed ratio exceeds a specified small value in a reverse drive direction, (iii) the vehicle is in an engine brake control state, on condition that the lever is placed in the neutral position and the actual speed ratio exceeds the specified small value in the forward or reverse drive direction, (iv) the vehicle is in an FR shift control state, on condition that the lever is placed in the forward or reverse drive position and the actual speed ratio exceeds the specified small value in the reverse or forward drive direction, and (v) the vehicle is in a neutral control state, on condition that the le

Abstract: The gearbox includes a multi-shaft toothed-wheel planetary gearing and a continuously adjustable hydrostatic transmission having toothed-wheel auxiliary transmission stages and gear-changing clutches. The hydrostatic transmission is associated with a displacement-type machine with constant displacement volume. In the planetary gearing, one shaft forms the input shaft to which the adjustable displacement-type machine is connected. A second shaft of the planetary gearing is connected to the constant-volume displacement-type machine. Third and fourth shafts of the planetary gearing represent coupling shafts. The coupling shafts alternately act via at least two auxiliary transmission stages, also called gears, on the output shaft. The coupling shafts change their speeds in such a manner that one coupling shaft becomes steadily faster and the other one becomes steadily slower. They behave in such a manner that they exhibit equal speeds in one extreme position.

Abstract: An arrangement and process for operating a continuously variable drive unit of a motor vehicle having an apparatus for control of the operation of the clutches (25, 26) in the mechanical transmission branch (19). Sensors (7, 9, 45) transmit the speed of the mechanical transmission branch (19), the hydrostatic transmission branch (17) and the transmission output shaft (10) to an electronic control device (3). The clutches (25, 26) are disconnected in the case of inadmissible speed ratios.

Abstract: Stepless hydromechanical mechanism with multiple power-transmission paths, more particularly for motor vehicles, having at least two switching ranges in which the stepless control of the mechanism is effected by a hydrostatic transmission, in which the specific requirements on the hydrostatic unit are reduced to a minimum. The hydrostatic power content is reduced. The parameters determining noise, efficiency and service life, i.e., hydrostatic pressure, hydrostatic speed, as well as the values of these components and their arrangement are brought into acceptable and technically feasible bounds.

Abstract: In a load change-over gear with infinitely variable transmission, which includes a linkage gear (1) driven by a main drive shaft (5), a control gear (2) associated with the linkage gear (1), as well as a switching or change-over gear (4) series-connected after the linkage gear (1), linkage shafts (10 and 11) can be alternately coupled to the switching gear (4). To create a variable switching logic and to save structural components of the switching gear (4), a superposition gear (3) is series-connected after the linkage gear (1) whose input shaft (14) can be coupled alternately to linkage shafts (10 and 11). Superposition gear (3), in which the main drive shaft rpm can be superposed on the rpm of the input shaft (14), in turn includes a linkage shaft (21) that can be coupled directly to a main output shaft (24) or to the switching gear (4).

Abstract: A hydromechanically infinitely variable transmission with power splitting for motor vehicles with at least five gearshift ranges. The transmission can be infinitely varied by means of a hydrostatic transmission. A hydrostat transmission, a multi-shaft summation planetary transmission and at least two downstream planetary transmission units constitute basic components which can be mutually coupled in transmission combinations of various configurations. The power summarized in the summarization planetary transmission is transmitted alternately through an intermediate shaft or coupling shaft and clutches to a planetary transmission unit. In at least one gearshift range, a shaft of the summarization planetary transmission is connected directly via a clutch to the output shaft. Depending on the embodiment, one to three reverse gear ranges can be incorporated in the transmission.

Abstract: A power transmission having a four-shaft double planetary gear (I, II), which is driven on the one hand via a turning gear (WG) and on the other via a variable-displacement gear (HG) and is connectable on the power take-off side via selectable ratio gears via controllable clutches (K1A-K7A) to a power take-off shaft (AW3) and is connectable on the power take-off side retroactively via two of the selectable ratio gears (G4, G5) by means of a startup clutch (K0B), as a result of which with the turning gear (WG) disengaged, a fully hydraulic startup range is provided, and the other gear ranges are mechanically-hydraulically split in terms of power when the turning gear is engaged.All the clutches are double claw clutches.The startup clutch has a special construction, with a sliding sleeve.The transmission is especially suitable for agricultural machines, because it is fully reversible. Other versions are shown.

Abstract: Arrangement and method of operating a variable drive unit with a selector switch for the preselection of a long-term speed and a control unit which allows for the continuous operation of a continuously variable power split transmission only at reduction ratios (.phi..sub.continuous) having a certain minimum interval (.phi..sub.min) from the reduction ratio at the shift points between the speed ranges in the mechanical branch of the transmission and the control unit changes the speed of the internal combustion engine in order to reach speeds lying within the minimum interval and controlled by changing the engine speed while maintaining reduction ratio of the transmission instant.

Abstract: A branched, infinitely variable hydromechanical transmission with multiple power-transmission paths for motor vehicles has an expanded first shift range to facilitate broadening of the overall gear-shift range to achieve higher power density and eliminates the need for a starting clutch. The transmission includes a first hydrostatic unit with an adjustable volume, a second hydrostatic unit, preferably with a constant volume, and one or more summation gear trains for adding together the power transmitted from the transmission input along hydraulic and mechanical power-transmission paths. The input shaft of the transmission is connected directly to the drive motor.

Abstract: A hydrostatic-mechanical power-distribution transmission with infinitely variable gear ratio in the hydrostatic branch and several ratios in the mechanical branch, which downstream of the coupling gear has shiftable planetary reduction gears for the purpose of reducing the power contribution of the hydrostatic branch in the starting range.