EP1418275B1 - Method for controlling a piste grooming vehicle and piste grooming vehicle - Google Patents

Abstract

u The skiing piste cleaning machine is in the form of a tracked vehicle fitted with a range of tools, eg leveller, bucket etc The vehicle has a processor [54] with a navigation system [56] and sensors to measure vehicle speed and track speed. The vehicle has a main drive [30] linked to a number of actuators [44,46,48,50,52].

Description

The invention relates to a method for controlling a piste grooming vehicle. The invention also relates to a piste grooming vehicle for carrying out the method according to the invention.

From the international patent publication WO 01/55511 A2 For example, a piste grooming vehicle is known in which a vehicle speed over a snow surface can be detected by means of a speed radar disposed on the vehicle. With this vehicle speed, the chain speed is compared and a slip is calculated from these values. Due to the calculated slip, a chain tension can be adjusted automatically. Furthermore, it is provided in the piste care vehicle described therein that an operator when using a half-pipe cutter a Target angle and a tolerance for the half-pipe cutter specifies. The actual working angle of the half-pipe cutter is monitored and the half-pipe cutter can be automatically controlled for compliance with the target angle. A snow depth under the vehicle can be detected by means of a radar penetrating to the ground and a map with snow depths can be created by combining the depth of snow detected by the radar and position data acquired by means of a GPS navigation system. The piste grooming vehicle has acquisition and display devices for a slope slope as well as for the setting of piste grooming equipment.

From the German patent application DE 100 45 524 A1 For example, a piste grooming apparatus for processing a snow surface is known. This piste grooming device has at least one sensor and a signal processing unit processing a sensor signal generated by the sensor, by means of which an actual condition of a processed snow surface is detected. The actual state is output by means of a corresponding display unit. The evaluation of the actual state of a snow surface, which has been processed for example with a plow blade, a milling cutter, a smoother or the like, is thus independent of capabilities of an operator of the piste grooming device.

With the invention, the operation of a snow grooming vehicle to be simplified.

According to the invention for this purpose a method for controlling a grooming vehicle, provided with a distribution of provided by a drive motor of a piste grooming vehicle drive power to a traction drive and other consumers, in which the distribution of the drive power is controlled by a central processing unit, wherein by means of the central processing unit a different distribution of the drive power as a function of a predeterminable, variable prioritization of the traction drive, at least one consumer and / or groups of consumers is adjustable.

By prioritizing the traction drive or consumers, it can be ensured, for example, that a piste grooming vehicle optimally prepares a track even when operated by an inexperienced driver, for example because a milling performance is always sufficient to achieve a desired snow surface condition. By prioritizing the mill, it is possible to avoid having too little milling power due to an operating error stands to achieve the desired result. On the other hand, for example, a stalling of the piste grooming vehicle on a steep slope can be avoided by prioritizing the traction drive by significantly reducing the drive power required for other consumers, for example a tail-mill, in critical situations. In addition to the traction drive consumers are for example a rear tiller, a front extractor, a dozer blade, a winch, a motor or oil cooling fan, a half-pipe cutter, a track maintenance device or the like. It is also possible to prioritize groups of consumers. For example, at steep sections and in winch operation, a winch and the drive can be prioritized. In order to maximize snow surface quality, a group of consumers consisting of the snow blade and a rear tiller could be prioritized.

In a further development of the invention, a prioritization of the travel drive, at least one piste grooming device and / or a winch is optionally adjustable.

In this way, a clear improvement is achieved by manageable tax expense. Thus, for example, in pure driving the drive can be prioritized, whereas in the care operation one or more piste grooming devices are prioritized. If the winch is used on steep sections, the winch is always prioritized. The prioritizations described already make it possible to avoid a large part of common operating errors.

In a development of the invention, threshold values for the drive power available to the further consumers and / or the traction drive can be predefined in the prioritization of individual consumers.

In this way, it can be prevented, for example, that a piste grooming vehicle stops when prioritizing piste grooming equipment, since insufficient drive power is available for the traction drive. Conversely, it can be prevented, for example, that prioritization of the traction drive achieves an insufficiently processed snow surface by ensuring that the track grooming equipment has sufficient drive power available for achieving a satisfactory result.

In a further development of the invention, it is provided that threshold values for output performance parameters of the travel drive, such as driving speed, and / or output power parameters of the further consumers, such as milling speed, can be predetermined.

By these measures, on the one hand, a still sufficient driving performance of the piste grooming vehicle and a still sufficient quality of the processed snow surface can be ensured.

In a further development of the invention it is provided that, depending on environmental parameters, such as slope, winch operation, snow density, snow temperature and / or snow depth, a conversion of the prioritization is proposed or automatically performed by the processing unit.

These measures greatly facilitate the operation of a piste grooming vehicle, since an operator is suggested or even relieved of the required changeover of prioritization. For example, in the case of transitions from flat pieces to steep sections, a switchover between a prioritization of snow grooming equipment and a prioritization of the traction drive should take place in order to prevent the snow grooming vehicle from getting stuck. By making such a change automatically is made depending on a slope, handling errors are avoided. As a result of the change of prioritization, for example, a milling depth of a rear tiller and / or a contact pressure can be automatically reduced. For example, depending on the slope, the position of a plow blade can be changed to prevent the so-called burial of the piste grooming vehicle. In addition, for example, in a transition from natural snow to artificial snow, which can be determined by the environmental parameters of snow density and snow temperature, a different prioritization and adjustment of the piste grooming equipment are made to always achieve an optimally processed snow surface.

In a further development of the invention, it is provided that, under the control of the central processing unit, a tuning of the setting of the drive motor, a driven by the drive motor hydraulic pump and a Hydrostatgetriebes the traction drive is made to obtain the desired distribution of drive power with low power loss.

These measures can be achieved by tuning engine, Pumpenund gearbox adjustment efficiency.

In a development of the invention, a brake power generated by means of a hydraulic brake or a hydraulic pump coupled to the wheel drive is distributed to the plurality of consumers under the control of the central processing unit.

In this way, for example when driving downhill, the drive of a rear tiller on the braking power done. As a result, the energy consumption of a snow grooming vehicle can be significantly reduced.

Advantageously, it is provided that predeterminable travel programs can be set by means of the central processing unit, on the basis of which the central processing unit proposes or automatically carries out an adjustment of a drive motor, a traction drive and / or further consumers, such as a piste grooming device or a cable winch.

The measures also allow an untrained operator of a piste grooming vehicle to achieve a desired snow surface or a desired piste profile. For example, a desired surface finish can be specified, and the central processing unit then adjusts the existing snow grooming equipment or suggests setting it so that the desired result is achieved. For example, a driving program for generating a Wedelstrecke with excessive curves are given, whereupon the central processing unit adjusts the drive, the dozer blade and a rear tiller suitable to achieve the desired contour and surface finish of the Wedelstrecke. Alternatively, a travel program can be set for transport purposes, with which a maximum driving speed is achieved. Furthermore, driving programs for achieving maximum climbing ability or minimum energy consumption are possible.

In a further development of the invention, the setting of the drive motor, the traction drive and / or other consumers within a driving program depending on environmental parameters, such as position of the piste grooming vehicle, snow depth, snow density and snow temperature, slope and the like.

In this way, by means of a driving program, for example, a fun park with a half-pipe router as a function of a GPS position (Global Positioning System) of the piste grooming vehicle. Another example is the different shape of humps depending on the slope. In addition, for example, when creating a ramp, a desired ramp angle can be achieved. It is also possible to work out a track with excessive curves at predefined positions in the terrain, which are determined by a GPS navigation system.

Advantageously, specifically for determining a snow density, the snow density is determined by means of a conductance measurement of the snow in the area of the snow grooming vehicle and a subsequent processing of the measured values in a central processing unit.

In this way, if necessary in connection with a snow temperature measurement, a distinction can be made between artificial snow and natural snow. For example, the distinction between fresh snow and old snow, harsch and the like is possible. This is important in a method for controlling a piste grooming vehicle for setting the piste grooming equipment.

In a development of the invention, a conductance measurement is carried out by means of at least two electrodes, which are in contact with the snow in the area of the piste care vehicle and are carried along with the piste grooming vehicle.

A conductivity measurement by means of at least two electrodes allows a reliable determination of the snow density with little effort. To improve the measurement result significantly more than two electrodes can be used to determine several measurements obtained.

Advantageously, it is provided that a measurement of the true driving speed over ground by means of a navigation system and that a measurement of a chain speed takes place, wherein in a central processing unit processing of the true driving speed and the chain speed for determining slip takes place.

In this way, a true driving speed can be determined reliably and by using standardized navigation systems. In this way, the slip can be determined reliably with simple means.

In a further development of the invention, it is provided that the central processing unit checks and optionally modifies a chain tension, a chain speed and / or settings of piste grooming devices as a function of the determined slip.

For example, in large slip a dozer blade and a cutter can be raised or a chain speed can be withdrawn.

In a development of the invention, the true driving speed is measured by means of a satellite navigation system, a terrestrial navigation system and / or an inertial navigation system as well as a processing of the acquired data in the central processing unit.

Various navigation systems or a combination of different navigation systems can be used to determine the true driving speed. Especially by a combination of different systems, a high accuracy of the determination of the Reach driving speed. As navigation systems, for example, the GPS system (Global Positioning System), a radio bearing or optical bearing with cameras of terrestrial reference points, and / or a coupling of the distance covered by a reference point can be used by means of a gyrocompass.

The invention also relates to a piste care vehicle with a drive motor, a drive and other consumers and means for distributing a drive power to the drive and / or the other consumers, in which a central processing unit is provided for controlling the means for distributing the drive power, the means for Predetermining a variable prioritization of the traction drive or other consumers in the distribution of the drive power has.

In a development of the invention, the central processing unit has devices for specifying threshold values for the drive power provided to the travel drive or other consumers and / or threshold values for output performance parameters of the travel drive and / or the further consumers.

In a development of the invention, means for detecting environmental parameters, such as slope, winch operation, snow density, snow temperature and / or snow depth, are provided in the snow grooming vehicle.

In a further development of the invention, the piste grooming vehicle according to the invention has a controllable hydraulic pump driven by the drive motor and a controllable hydrostatic transmission for the traction drive and the central processing unit has means for tuning the setting of the drive motor, the hydraulic pump and the hydrostatic transmission of the traction drive in terms of low power loss.

In a further development of the invention, the piste grooming vehicle according to the invention is provided with a hydraulic brake or a hydraulic pump coupled to the wheel drive, and the central processing unit has means for distributing a braking power generated by the hydraulic brake or by the hydraulic pump to the plurality of consumers.

Advantageously, the snow grooming vehicle according to the invention is provided with means for measuring snow density, the means for measuring the snow density having at least two electrodes arranged in the form of a rake for measuring the conductivity of the snow.

Such a rake can for example be dragged or placed under the piste grooming vehicle and allows a reliable conductance determination of the snow in the area of the piste grooming vehicle. When using multiple electrodes, multiple readings can be collected and averaged. The arrangement of the electrodes in the form of a rake, for example, also allows the simultaneous detection of the snow temperature by means of a temperature sensor arranged in the region of the electrodes.

Fig. 1

eine Seitenansicht eines erfindungsgemäßen Pistenpflegefahrzeugs mit Räumschild und Heckfräse,

Fig. 2

ein erfindungsgemäßes Pistenpflegefahrzeug mit Frontschleuderfräse und Heckfräse,

Fig. 3

ein erfindungsgemäßes Pistenpflegefahrzeug mit Räumschild, Seilwinde und Heckfräse,

Fig. 4

eine Vorderansicht eines erfindungsgemäßen Pistenpflegefahrzeugs mit Half-Pipe-Fräser und

Fig. 5

ein Blockschaltbild eines erfindungsgemäßen Pistenpflegefahrzeugs.

Further features and advantages of the invention will become apparent from the claims and the following description of a preferred embodiment of the invention taken in conjunction with the drawings. In the drawings show:

Fig. 1

a side view of a piste grooming vehicle according to the invention with plow blade and rear tiller,

Fig. 2

a piste grooming vehicle according to the invention with a front-end grinder and rear-end mill,

Fig. 3

an inventive piste grooming vehicle with plow blade, winch and rear tiller,

Fig. 4

a front view of a piste grooming vehicle according to the invention with half-pipe cutter and

Fig. 5

a block diagram of a piste grooming vehicle according to the invention.

The invention will now be described in connection with FIGS Fig. 1 to 5 explained. While the Fig. 1 to 4 shows a piste grooming vehicle with different piste grooming equipment, should the Fig. 5 clarify the functional relationships between the individual components.

According to Fig. 1 a piste care vehicle 10 is provided with a plow blade 12. The plow blade 12 can be adjusted in a conventional manner in its setting relative to the piste care vehicle 10 by means of hydraulic cylinders. The piste grooming vehicle is further equipped with a rear tiller 14 and a so-called finisher 16. In a likewise conventional manner, an adjustment of the rear tiller 14 and of the finisher relative to the piste care vehicle 10 can be adjusted by means of hydraulic cylinders, and a milling speed of the rear tiller 14 can be changed. The piste grooming vehicle 10 has one in the Fig. 1 invisible drive motor that drives a hydraulic pump. The hydraulic power generated by the hydraulic pump is distributed by suitable means to the individual consumers, such as a travel drive for tracks 18, the milling drive of the rear grinder 14, the hydraulic cylinder for adjusting the dozer blade 12 and the rear tiller 14 and the finisher 16 and a chain tensioning system for the tracks 18. Other consumers include fans for engine cooling and hydraulic oil cooling. Furthermore, the piste care vehicle 10 is provided with a receiver 20 for a satellite navigation system, which in the Fig. 1 is merely indicated. Other sensors detect a slope, which means a slope of the snow grooming vehicle 10 about the longitudinal axis and about a transverse axis. Furthermore, the piste care vehicle 10 may have facilities for storing a terrain profile, so that based on the determined by means of the satellite navigation system or other navigation system current position and a current direction of travel, a forward-looking attitude of the piste grooming equipment and possibly other consumers can be made. For example, when an increase is imminent, a fan speed may already be increased, a vehicle speed may be decreased, and the piste grooming equipment may be gradually brought into the required position for the steep ride. The piste care vehicle 10 also has sensors for determining the conductance of the snow and the snow temperature in the area of the piste care vehicle 10. Suitable devices for this purpose can be designed, for example, in the form of a plurality of electrodes and / or temperature sensors, which are brought into contact with the snow in the form of a rake in the region of the finisher 16 or under the vehicle 10 itself.

In the Fig. 2 to 4 the piste grooming vehicle 10 is shown, which is equipped with other components. That's how it shows Fig. 2 the piste maintenance vehicle 10, the place of the plow of the Fig. 1 equipped with a front extractor 22. In the Fig. 3 the piste care vehicle 10 is equipped with a winch 24. The front view of the Fig. 4 shows the Pistenpflegefahrzeug 10, which is provided instead of the plow blade with a half-pipe cutter 26.

The block diagram of Fig. 5 shows the individual components of the piste grooming vehicle and their links. Thus, a drive motor 30 drives a hydraulic pump 34 via a shaft 32. The hydraulic fluid delivered by the hydraulic pump 34 is distributed to the various consumers by means of a distributor 36. It should be noted that in the presentation of the Fig. 5 Hydraulic lines are shown with large line width. In contrast, signal connections are shown with smaller line width as well as arrows or double arrows.

Through the distributor 36, the drive power of the drive motor 30 is distributed, for example, to a right-hand drive 38 and a left drive 40. Furthermore, a right chain tensioner 42 and a left chain tensioner 44 are supplied with drive power. The chain tensioners 42 and 44 are provided for varying the chain tension of the right and left drive chains, which is driven by a respective drive 38 and 40, respectively. On the traction drives 38, 40, a hydraulic brake 39, 41 is provided, implemented by the downhill power the kinetic energy of the piste grooming vehicle and consumers, such as a piste grooming device, are provided. This can significantly reduce energy consumption.

As a further consumer to the manifold 36, a rear tiller 46 with finisher and a front piste grooming device 48 are connected. The front piste grooming device may be in accordance with Fig. 1 to 4 be designed as a dozer blade 12, as a front extractor 22 or as a half-pipe cutter 26. Finally distributes the distributor 36, the drive power still on a winch 50 and fan 52, with engine cooling fan and oil cooler fan in the Fig. 5 are shown summarized.

The piste grooming vehicle has a central processing unit 54, which performs numerous control and regulation functions in the piste grooming vehicle 10 and is equipped, for example, with microprocessors and storage devices. The central processing unit 54 receives from all in Fig. 5 shown components of the snow grooming vehicle information signals and also outputs to these components control signals to make appropriate adjustments to these components. The information exchange between the components and the processing unit 54 is indicated by arrows or double arrows. In this context, it should be noted that in the Fig. 5 simplified function blocks shown, namely the travel drives 38, 40, the chain tensioner 42, 44, the slope maintenance equipment 46, 48 at the rear or at the bow of the piste maintenance vehicle and the winch 50 and the fan 52 also include the required control units and sensors, for example, the current Position to send the current speed or similar parameters from one of the function blocks to the central processing unit 54 and vice versa from the central processing unit 54 to receive control signals and implement them in appropriate control units and thereby, for example, a position of a piste grooming device via the control of hydraulic cylinders or To change milling speed via control of a milling motor. In addition, the drive motor 30, the hydraulic pump 34, and the manifold 36 are also provided with appropriate sensors and control units to provide the central processing unit 54 with information about the current settings and parameters and to convert control signals from the central processing unit 54 to the desired settings can. For example, the central processing unit 54 coordinates the settings of the drive motor 30, hydraulic pump 34 and traction drives 38, 40 in terms of the best possible efficiency. For example, a delivery rate of the hydraulic pump 34 and a gear ratio Hydrostatgetrieben in the traction drives 38, 40 are coordinated.

The central processing unit 54 also receives input from one or more navigation systems 56 to determine a current position of the piste grooming vehicle. In a conventional manner, by means of the navigation systems 56 and the central processing unit 54, it is also possible to determine a position of the piste grooming vehicle on a stored soil profile in order to obtain information about the terrain to be expected, depending on the current direction of travel of the piste grooming vehicle. The navigation systems 56 may include, for example, a satellite navigation system, a terrestrial navigation system, for example by means of radio or optical bearing of reference points, as well as an inertial navigation system, in which a position determination by means of a gyrocompass and the distance traveled since a known reference point distances.

Furthermore, the central processing unit 54 receives sensor signals of a tilt sensor 58, by which a slope can be determined via the inclination of the vehicle about its longitudinal axis and about its transverse axis.

In addition, a measuring rake 60 is provided, which has a plurality of measuring electrodes, which are arranged at a distance from each other and can be brought into contact with the snow in the area of the piste grooming vehicle. Between the electrodes of the measuring computer 60, a conductance of the snow is measured and transferred to the central processing unit 54. In response to a control signal from the central processing unit 54, the metering rake 60 may be lowered or raised into the snow. Furthermore, snow temperature sensors 62 are provided, which are expediently also fastened to the measuring rake 60 are, so that together with a conductivity measurement, the temperature of the snow can be detected. From the detected conductance and snow temperature, the central processing unit 54 can classify the snow in the area of the piste grooming vehicle, for example whether artificial snow or natural snow exists, and then specify suitable settings for the piste grooming equipment.

The central processing unit 54 also receives information from a snow depth measurement system 64. Depending on the detected snow depth, the central processing unit 54 may specify settings for snow grooming equipment, for example altering a position of the snow blade to remove snow from areas of high snow depth and into areas of low snow depth move.

Finally, a display and input device 66 is provided, on which information transmitted by the central processing unit 54 can be displayed and by means of which an operator can specify settings. The settings desired by the operator are transmitted in the form of signals to the central processing unit 54, which then provides the desired adjustment of the components. Via the display and operating unit 66, for example, settings proposed by the central processing unit 54 for piste grooming equipment and driving speed can be displayed, and an operator then has the option of accepting the proposal or of automatically making an adjustment. In addition, it is also possible that the central processing unit 54 automatically makes required settings and informs the operator about the settings made via the display and operating unit 66.

Claims (20)

1. A method for controlling a ski-run-maintenance vehicle having a distribution of drive power provided by a drive engine (30) of the ski-run-maintenance vehicle (10) to the propulsion drives (38, 40) and other consumers (42, 44, 46, 48, 50, 52) of the ski-run-maintenance vehicle (10), where the distribution of drive power is controlled by a central processing unit (54), characterized in that a varying distribution of drive power depending upon a prescribable, variable prioritisation of the propulsion drives (38, 40), at least one consumer, and/or groups of consumers may be set using the central processing unit (54).
2. A method according to claim 1, characterized in that a prioritisation of the propulsion drives (38, 40), at least one ski-run-maintenance device (48, 46), and/or a winch (50) may be optionally set.
3. A method according to claim 1 or claim 2, characterized in that thresholds for the drive power made available to other consumers and/or propulsion drives (38, 40) may be prescribed in conjunction with the prioritisation of individual consumers (46, 48, 50) or propulsion drives (38, 40).
4. A method according to any of the foregoing claims, characterized in that threshold values of output-power parameters of the propulsion drives (38, 40), such as travel speed, and/or output-power parameters of the other consumers (46, 48, 50, 52), such as rotation rates, may be prescribed.
5. A method according to any of the foregoing claims, characterized in that a change in prioritisation depending upon the values of ambient parameters, such as slope gradient, winch actuation, snow density, snow temperature, and/or snow depth, is proposed by the operator or automatically instituted by the processing unit (54).
6. A method according to any of the foregoing claims, characterized in that a coordination of the settings of the drive engine (30), a hydraulic pump (34) driven by the drive engine (30), and a hydrostatic drive of the propulsion drives (38, 40) controlled by the central processing unit (54) is instituted in order to obtain the desired distribution of drive power, combined with low power losses.
7. A method according to any of the foregoing claims, characterized in that braking power generated by a hydraulic brake (39, 40) or hydraulic pump (38, 40) coupled to the sprocket drive is distributed to the several consumers (46, 48, 52), controlled by the central processing unit (54).
8. A method according to any of the foregoing claims, characterized in that prescribable travel programmes, can be set by the central processing unit (54), by means of which the central processing unit (54) will automatically execute or propose to the operator settings of a drive engine (30), a propulsion drive (38, 40), and/or other consumers, such as a ski-run-maintenance device (46, 48) or winch (50).
9. A method according to claim 8, characterized in that the settings of the drive engine (30), propulsion drives (38, 40), and/or other consumers (42, 44, 46, 48 ,40 ,52) under a given travel programme are correlated to the values of ambient parameters, such as the location of the ski-run-maintenance vehicle (10), snow depth, snow density, slope gradient, and similar.
10. A method according to any of the foregoing claims, characterized in that snow density is determined by measuring the electrical conductivity of the snow in the vicinity of the ski-run-maintenance vehicle (10) and subsequently processing the measured values on a central processing unit (54).
11. A method according to claim 10, characterized in that electrical-conductivity measurements employ at least two electrodes (60) that are in contact with the snow in the vicinity of the ski-run-maintenance vehicle (10) and carried along by the ski-run-maintenance vehicle (10).
12. A method according to any of the foregoing claims, characterized in that a measurement of true ground speed by means of a navigation system (56), and a measurement of a tread speed is carried out, and processing of true ground speed and tread speed by a central processing unit (54) in order to determine slippage rate.
13. A method according to claim 12, characterized in that the central processing unit (54) checks a tread tensioning, a tread speed, and/or the settings of ski-run-maintenance devices (46, 48) and/or a winch (50), and varies them, if necessary, depending upon the slippage rate determined.
14. A method according to claim 12 or claim 13, characterized in that measurement of true travel speed employs a satellite navigation system (56), a terrestrial navigation system (56), and/or an inertial navigation system (56), along with processing of the acquired data by the central processing unit (54).
15. A ski-run-maintenance vehicle having a drive engine (30), a propulsion drive (38, 40), other consumers (42, 44, 46, 48, 50, 52), means (34, 36) for distributing drive power to the propulsion drive and/or other consumers, and a central processing unit (54) for controlling the means (34, 36) for distributing drive power, characterized in that the central processing unit (54) has facilities for prescribing a variable prioritisation of the propulsion drive or other consumers in conjunction with the distribution of drive power.
16. A ski-run-maintenance vehicle according to claim 15, characterized in that the central processing unit (54) has facilities for prescribing thresholds for the drive power made available to the propulsion drive or other consumers and/or threshold values of output-power parameters of the propulsion drive and/or other consumers.
17. A ski-run-maintenance vehicle according to claim 15 or claim 16, characterized in that means (58, 60, 62, 64) for acquiring the values of ambient parameters, such as slope gradient, winch actuation, snow density, snow temperature, and/or snow depth are provided.
18. A ski-run-maintenance vehicle according to any of the foregoing claims 15 to 17 having a controllable, hydraulic pump (34) driven by the drive engine and at least one controllable, hydrostatic drive for operating the propulsion drives (38, 40), characterized in that the central processing unit (54) has facilities for coordinating the settings of the drive engine (30), the hydraulic pump (34), and the at least one hydrostatic drive of the propulsion drive (38, 40) in the interest of reducing power losses.
19. A ski-run-maintenance vehicle according to any of the foregoing claims 15 to 18 having at least one hydraulic brake (39, 41) or a hydraulic pump coupled to the sprocket drive, characterized in that the central processing unit (54) has facilities for distributing a braking power generated by the at least one hydraulic brake (39, 41) or the hydraulic pump to the several consumers (46, 48).
20. A ski-run-maintenance vehicle according to any of the foregoing claims 15 to 19, characterized in that means for measuring snow density involving at least two electrodes for measuring electrical conductivity arranged in the form of a rake (60) are provided.

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