Hydraulic catapult drive

The invention relates to a catapult drive for an object to be accelerated, preferably the car of a fairground ride, wherein the object is accelerated by means of a driving element. The movement of the driving element is produced by a flexible drive and a hydraulic cylinder via which all movements of the driving element can be controlled. The invention also relates to a control system for suitably controlling the inventive catapult drive.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a hydraulic catapult drive in accordance with the preamble of claim1.

2. Description of the Related Art

Hydraulic catapult drives of this type are used for accelerating an object, for instance an aircraft along a launching pad or a passenger train of a roller coaster or the like. In WO 01/66210 A1 a catapult drive is shown by which a car of a fairground ride can be accelerated along an acceleration track. The catapult drive comprises a driving car driven by a hydraulic motor and a flexible drive on which the car to be accelerated is supported. The hydraulic motor drives a winch which is wrapped in opposite sense by two pull ropes both of which act upon the car. Upon acceleration one of the pull means is wound on the winch, while the other pull rope correspondingly unwinds. When resetting the car into its home position the direction of rotation of the hydraulic motor is reversed so that the former pull rope is wound and the latter pull rope is unwound. The flexible drive is tensioned via a tensioning rope of a further flexible drive during acceleration and resetting.

U.S. Pat. No. 6,837,166 B1 discloses a catapult drive for a fairground ride in which the driving element is accelerated via a flexible drive and a hydraulic cylinder by which a movable set of pulleys of the flexible drive is axially movable. In this catapult drive, at the driving element a pull rope of a further flexible drive is additionally fixed the end portions of which similar to the afore-described embodiment—can be wound onto a winch or unwound from the same so that the driving element is reset to the home position by appropriately driving the winch, wherein then also the hydraulic cylinder is returned to its home position by the movable set of pulleys.

In WO 2004/024562 A1 a catapult drive is disclosed in which the acceleration of the driving element takes place via a flexible drive and a hydraulic cylinder in the form of a differential cylinder the bottom-side cylinder chamber of which can be pressurized by the pressure in a high-pressure reservoir when extending the piston rod. The piston rod of the differential cylinder supports two movable sets of pulleys which are wrapped by a common pull rope to which the driving element is fixed. The hydraulic cylinder is reset to its home position via a separate resetting cylinder which is likewise in the form of a differential cylinder and the piston rod of which returns that of the differential cylinder used for acceleration against the force applied by the hydraulic reservoir to its home position.

The above-described catapult drives require a comparatively high expenditure in terms of devices, because for acceleration and resetting of the driving element different actuating members are used which have to be controlled in an appropriate manner.

OBJECT OF THE INVENTION

Compared to this, the object underlying the invention is to provide a simply structured catapult drive via which a driving element acting upon an object to be accelerated is accelerated and can be reset to its home position.

This object is achieved by a hydraulic catapult drive in accordance with the preamble of claim1.

According to the invention, the hydraulic catapult drive comprises a driving element which can be moved into the direction of acceleration and in the direction of resetting via a flexible drive and a hydraulic cylinder driving the latter. The flexible drive has two sets of pulleys movable by the hydraulic cylinder and wrapped in sections by at least one pull means so that, depending on the control of the hydraulic cylinder, a pulling force for acceleration can be transmitted via a set of pulleys and the pull means and, respectively, a pulling force for resetting can be transmitted via the other set of pulleys. The driving element can be decelerated or accelerated in both directions of movement.

In accordance with the invention, the acceleration and the resetting movement is performed with the aid of a single hydraulic cylinder on which two movable sets of pulleys of the flexible drive are disposed. In contrast to the afore-described prior art—in such a solution no separate drive is required for resetting the driving element so that the expenditure in terms of devices is substantially reduced vis-à-vis these solutions.

In an embodiment of the invention a pull rope which is then deflected at the respective driving element can be allocated to each set of pulleys. Accordingly, in this embodiment at least two pull means or pull ropes act upon the driving element.

In an alternative solution both sets of pulleys of the flexible drive are wrapped by a common pull means to the central portion of which the driving element is fixed.

In both solutions the free ends of the pull rope or ropes are rigidly or movably anchored. Between the end of the pull means and the anchoring a spring element or a clamping cylinder may be arranged to avoid loosening of the pull means and to compensate for variations in length.

When using clamping cylinders, they can be pressurized by the pressure in the respective allocated pressure chamber of the hydraulic cylinder or can be controlled by a separate system.

Depending on the building space available, the movable pulleys and the fixed deflection pulleys of the flexible drive allocated to the former can be arranged approximately in extension of the hydraulic cylinder or laterally with respect the same.

In a particularly preferred embodiment the hydraulic cylinder is an equal area cylinder or has two piston rods of different diameter, wherein one of the sets of pulleys is disposed on each piston rod. It is the advantage of such solution that the piston rods of a cylinder of this type are subjected to tensile load only so that the piston rod is prevented from buckling.

Instead of a cylinder including two piston rods, also a differential cylinder can be used with both sets of pulleys being arranged at the only piston rod thereof. This piston rod then is pressurized in one direction of movement (acceleration or resetting).

In order to avoid excessive loads of the hydraulic drive, the hydraulic cylinder can have an end-of-travel damping integrated in the hydraulic cylinder or formed separately thereof.

The hydraulic cylinder is controlled by a control system, wherein in an embodiment a pressure chamber of the hydraulic cylinder increasing upon acceleration can be connected via the control system to a high-pressure reservoir and/or a high-pressure pump and the pressure chamber of the hydraulic cylinder increasing upon resetting can be connected to a low-pressure reservoir and/or a low-pressure pump.

It is preferred in this context that the high-pressure pump is a variable-displacement pump.

In the control system according to the invention for controlling the hydraulic cylinder in the inlet to the pressure chamber of the hydraulic cylinder increasing upon acceleration and in the discharge from the pressure chamber diminishing upon acceleration a respective proportionally variable control valve is arranged by which the inlet and the discharge can be blocked and/or in response to the accelerating weight an opening cross-section to the hydraulic medium connection of the respective pressure chamber to a hydraulic medium source or a hydraulic medium sink can be increased in a controlled manner.

In an especially preferred embodiment the control system in addition includes a continuously variable resetting control valve by which upon resetting the driving element the increasing pressure chamber of the hydraulic cylinder can be connected to the low-pressure pump and the diminishing pressure chamber can be connected to the hydraulic medium sink. Since this resetting movement is comparatively slow, the continuously variable resetting valve can be designed to have a lower nominal size than the afore-mentioned proportionally variable control valves.

In an advantageous solution the control system includes a check valve by which a hydraulic medium flow path from the discharge to the pressure chamber increasing upon acceleration can be increased in a controlled manner upon deceleration of the driving element after the accelerating phase, wherein the allocated proportionally variable control valve is by-passed. It is possible in this way to move said control valve for deceleration into a closing position and to allow hydraulic medium to flow from the discharge into the allocated pressure chamber.

In a further preferred solution between each control valve and the allocated pressure chamber a respective pilot-controlled logic valve which permits a leak-free sealing of the pressure chambers is disposed in the hydraulic medium flow path.

The hydraulic cylinder is preferably arranged in an open hydraulic circuit.

The applicant reserves itself to direct a separate independent claim to the control system per se comprising the proportionally variable directional control valves, the check valve, the additional continuously variable reset control valve and/or the other component parts, wherein said hydraulic component parts can be claimed in any combination and independently of the structure of the gear arranged between the driving element and the hydraulic cylinder.

Hereinafter preferred embodiments of the invention are illustrated in detail by way of schematic drawings, in which

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows a circuit diagram of a hydraulic catapult drive1for a car or a passenger train of a roller coaster or the like. Said car is accelerated via a driving element2driven by the catapult drive1. In the shown embodiment a flexible drive4which is driven by a hydraulic cylinder6acts upon both sides of the driving element2. The hydraulic cylinder is an equal area cylinder in the shown embodiment. The hydraulic medium supply of the hydraulic cylinder6takes place via a control system8by which two pressure chambers10,12of the hydraulic cylinder6can be communicated with a hydraulic medium source14or a hydraulic medium sink formed by a tank T in the shown embodiment. The control system8is in the form of an open circuit. Further details of the catapult drive will be illustrated hereinafter by way of the enlarged views inFIGS. 2 and 3.

FIG. 2shows the flexible drive4including the hydraulic cylinder6for moving the driving element2, the latter being moved in the direction of the arrow for acceleration and is reset in the opposite direction. As mentioned in the foregoing, the hydraulic cylinder6is a an equal area cylinder in this embodiment by the pistons of which including the two piston rods16,18the cylinder is divided into the two pressure chambers10,12which are designed as respective annular chambers. For accelerating the driving element2the piston is moved to the right in the view according toFIG. 1so that the pressure chamber10is increased, while the pressure chamber12located on the right (FIG. 2) is correspondingly reduced. In the shown embodiment the diameters of the piston rods16,18are equal. On principle, they may also have different diameters.

At the end portions of the piston rods16,18protruding from the hydraulic cylinder6a respective movable set of pulleys20and22of the flexible drive4is mounted which is appropriately displaceable by the in and out travel movement of the piston rods16,18. A set of deflection pulleys24and/or26is allocated to each set of pulleys20,22. Each of said sets of deflection pulleys24,26is supported in a stationary manner on the frame of the roller coaster or on a base.

The sets of pulleys22,26and20,24allocated to each other are wrapped by a respective pull means, for instance a pull rope28,30acting with an end portion upon the driving element2so that via the pull rope28the driving element2is moved in the direction of acceleration, while resetting is performed by means of the pull rope30. There can also be used one single continuous pull rope28, wherein in that case the driving element2is detachably fixed to the same. The pull rope28can then be pulled through the driving element2so that an exchange of the rope is simplified.

The respective other end portions of the two pull ropes28,30are anchored in turn at the frame/base. In the shown embodiment they are anchored via a respective clamping cylinder32,34in the form of a differential cylinder. By said clamping cylinders32,34variations of length of the pull ropes28,30can be compensated and a continuous tension can be adjusted. The clamping cylinder32,34has an annular chamber38and/or36connected via a clamping line40and/or42to the respective adjacent pressure chamber10(clamping line40) and/or12(clamping line42). In this way it is ensured that the pull rope28,30exerting a pulling force on the driving element2upon acceleration or resetting is tensioned by the respective pressure in the correspondingly increasing pressure chamber10,12.

Of course, also other clamping members, for instance pneumatic clamping cylinders, clamping springs etc. can be employed. Basically also a “rigid” but adjustable anchoring of the respective pull rope is possible.

A respective block and tackle is formed by the pull ropes28,30and the two sets of pulleys22,26;20,24wrapped by the same. In the shown embodiment each of the two movable sets of pulleys20,22includes 4 rope pulleys44and the fixed sets of pulleys24,26include 4 rope pulleys46so that accordingly an eightfold pulley ratio is provided. Consequently, the stroke of the piston rods16,18is transmitted via the flexible drive4such that the driving element2covers the eightfold distance along the track of motion. Accordingly, the pulling force transmitted from the driving element2to the car to be accelerated is merely ⅛ of the force applied by the hydraulic cylinder6.

In the shown embodiment between the driving element2and the set of deflection pulleys26two further stationary guide pulleys48,50are provided by which the pull rope30is aligned with respect to the track of motion of the driving element2. In the pull rope28active in the direction of acceleration merely one stationary guide pulley52is provided. The movable sets of pulleys20,22can be guided or supported in an appropriate manner.

In the shown embodiment the movable sets of pulleys22,20are supported on a joint cross-beam54and/or56indicated in dash-dot line which in turn is fixed to the respective allocated piston rod16and/or18. Of course, the pulleys44of the movable sets of pulleys20,22can also be arranged to be coaxially juxtaposed, wherein the deflection pulleys46are then correspondingly aligned.

For accelerating the driving element2the piston of the hydraulic cylinder6is moved to the right so that, accordingly, the movable set of pulleys20is likewise shifted to the right and the distance between the movable set of pulleys20and the set of deflection pulleys24is increased and, accordingly, the driving element2is accelerated in arrow direction. Also the movable set of pulleys44is shifted to the right toward the set of deflection pulleys26, the pull rope30also moving via the moving driving element2and being kept tensioned by the cylinder32.

In the represented embodiment the piston rods16,18are supported by a hydrostatic bearing58,60in the bottom of the cylinder6. As hydrostatic bearings of this type are known to those skilled in the art, respective explanations can be dispensed with. The hydraulic cylinder6is preferably also designed to include end-of-travel damping means that are either integrated in the hydraulic cylinder6or are externally arranged.

In the solution shown inFIG. 2all necessary movements of the driving element2are controlled via the hydraulic cylinder6—the catapult drive1thus has a substantially simpler design than the prior art described in the beginning.

The control of the hydraulic cylinder6is explained by way ofFIG. 3illustrating a circuit diagram of the control system8of the hydraulic cylinder6.

In the embodiment according toFIG. 1, as can be taken in detail fromFIG. 4, the hydraulic medium source14is formed by a pump system comprising a variable-displacement pump62, a constant-displacement pump64and a high-pressure reservoir66. The constant-displacement pump64and the variable-displacement pump62are preferably driven by a joint motor M. A check valve67is arranged downstream of the pressure port of the constant-displacement pump64. Moreover, a pilot-controlled pressure-limiting valve68and/or69including directional control valve relief is connected to each pressure port. The pressure ports of the variable-displacement pump62and of the high-pressure reservoir66are connected via a high-pressure pump line70to a pressure port P1of a control block72accommodating the control system8(indicated in dash-dot line). The pressure port of the constant-displacement pump64is connected to a further pressure port P2of the control block72via a low-pressure pump line74. The control block further comprises a tank port T connected to the tank T via a tank line76and a back-flow valve78. According toFIG. 3, a cooler71can further be provided in the tank line76. In the area between the tank port T and the back-flow valve78a low-pressure hydraulic reservoir80is connected by which pressure variations in the tank line76can be compensated. The back-flow valve78ensures that the tank line76is somewhat biased.

Moreover, at the control block72a control port X and an oil-leakage port Y are provided, the latter being connected to the tank T. In the shown embodiment the control port X is connected to the high-pressure pump line70so that the pressure prevailing there acts as control pressure. Basically, also an external control pressure can be supplied.

Inside the control block72the pressure port P1is connected via a supply line82to the input port A of a proportionally variable control valve84hereinafter referred to as acceleration control valve84. It is electro-hydraulically pilot-controlled, wherein the control pressure is tapped off the control port X via a control line86. The leakage oil can flow off via an oil-leakage line87to the oil-leakage port Y. Said acceleration control valve84can be in the form of a pilot-controlled proportionally variable logic valve, for example. A port B of the acceleration control valve84is connected to the pressure chamber10of the hydraulic cylinder6via an advance line88and a logic valve90. In its spring-biased home position the acceleration control valve84seals the hydraulic medium communication to the advance line88in a leak-proof manner. A supply metering orifice defining the hydraulic medium volume flow is increased in a controlled manner by appropriately controlling the acceleration control valve84.

The logic valve90disposed in the advance line88is likewise designed to be pilot-controlled, wherein in a cover92of the logic valve90a shuttle valve94is arranged the two inputs of which are pressurized by the pressures at the port A and/or at the port B of the logic valve90so that the respective higher pressure is transmitted. The output of the shuttle valve94is connected to the input of a pilot valve96. It is in the form of a 4/2 directional switch valve and connects in its spring-biased home position the output of the shuttle valve94to the spring chamber98of the logic valve90so that the latter is biased in closing position and blocks the hydraulic medium flow path toward the annular chamber10. Upon change-over of the pilot valve96the spring chamber98is connected to the control oil tank line97so that the spring chamber98is pressure-relieved and can open the logic valve90. The opening movement of the piston of the logic valve90can be detected by a limit switch100. In this switching position of the pilot valve96moreover the connection from the output of the shuttle valve94to the spring chamber98of the logic valve90is blocked. The pressure prevailing in the advance line88is detected via a pressure sensor102.

A discharge line104whose pressure can be detected via a further pressure sensor106and in which a further logic valve108is provided having practically the same structure as the logic valve90is connected to the pressure chamber12of the hydraulic cylinder6. I.e. the higher pressure at the ports A, B of the logic valve108is tapped off by a shuttle valve110and is reported to a spring chamber114of the logic valve108in a home position of a pilot valve112. By change-over of the pilot valve112the spring chamber114is connected to the control oil tank line87and is thus pressure-relieved so that the logic valve108can be opened by the pressure applied to the pressure port B or A. The port A of the logic valve108is connected to an output port B of a further continuously variable control valve, hereinafter referred to as discharge control valve116the structure of which is similar to that of the acceleration control valve84so that further explanations can be dispensed with. A discharge line118leading to the tank port T is connected to the port A of the discharge control valve116.

In order to avoid pressure excesses in the advance line88and/or in the return line104they can be connected to each other via two pilot-controlled pressure-limiting valves120,122, wherein the maximum pressure is produced by appropriate adjustment of a pilot valve124,126.

In the control system shown inFIG. 3the resetting motion of the driving element, i.e. the axial displacement of the piston of the hydraulic cylinder6to the left is performed with the aid of a continuously variable reset control valve128. It has four ports, wherein a pressure port P is connected via a reset line130to the second pressure port P2of the control block72and a tank port T is connected via a reset tank line132to the discharge line118. Two working ports A, B are connected via a reset advance line134to the return line104and via a reset return line136to the advance line88, the valves84,116;90,108being by-passed. In each of the lines134,136a respective releasable check valve138,140is provided. In its spring-biased home position the reset control valve128connects its two working ports A, B to the reset tank line182, the check valves138,140blocking a hydraulic medium flow from the return line104or from the advance line88to the working ports A, B of the reset control valve128. By an appropriate pilot-control of the reset control valve128the same is shifted into one of its positions marked by (a) in which the pressure port P is connected to the working port B and the working port A is connected to the tank port T so that hydraulic medium is conveyed from the constant-displacement pump64through the low-pressure pump line74, the reset line130, the reset advance line134, the return line104into the pressure chamber12and, accordingly, the hydraulic medium displaced from the pressure chamber10flows through the advance line88, the reset return line136, the opened stop valve140, the working port A, the discharge line118, the tank line76and the backflow valve78to the tank T, the tank line76being biased via the backflow valve78.

By shifting the reset control valve128to one of its positions marked by (b) the hydraulic cylinder6can be adjusted also in the direction of acceleration via the constant-displacement pump64.

The shown control system8moreover comprises a check valve142disposed in a filling line144connecting the reset tank line132to the advance line88. Said check valve142is likewise in the form of a logic valve in the represented embodiment, wherein the pressure prevailing in the advance line88is reported to its spring chamber146.

For the purpose of a better comprehension, the function of the control system shown inFIG. 3is illustrated by way of the different phases of motion of the driving element2.

For accelerating the driving element2the acceleration control valve84and the discharge control valve116are opened in a controlled manner, wherein the increased cross-section may vary in response to the weight of the passenger car due to the number of passengers so as to adjust a predetermined acceleration profile. The variable-displacement pump62is driven by the motor M and hydraulic medium is conveyed into the high-pressure pump line70. The two pilot valves96and112of the logic valves90,108are changed over so that the hydraulic medium is conveyed via the opening logic valve90and the advance line88into the pressure chamber10so that the piston of the hydraulic cylinder6is moved to the right and—as explained in the beginning—the driving element2is accelerated by the pull rope28in the direction of the arrow (FIG. 1) by the increase in the distance between the movable set of pulleys20and the allocated set of deflection pulleys24so as to set the car to its initial speed. The hydraulic medium from the decreasing annular chamber12flows via the return line104to the logic valve108, wherein the pressure in the return line104acts upon the annular surface of the piston of the logic valve108and moves the same to its opening position so that the hydraulic medium flows off toward the tank T via the increased discharge control valve116, the discharge line118, the tank line76and the backflow valve78. The control valves84,116are driven such that the desired speed or acceleration profile is brought about.

At the end of the accelerating phase the driving element2is decelerated. For this purpose, the acceleration control valve84is closed and the discharge control valve116is closed in a controlled manner so that a predetermined decelerating speed profile is observed. The speed of the piston of the hydraulic cylinder6is adequately reduced, the volume of the pressure chamber10(accelerating pressure chamber) being further increased—the amount of hydraulic medium required for filling said pressure chamber10can then flow in through the opening check valve142from the discharge line118so that the filling takes place in the decelerating phase despite a closed or almost closed acceleration control valve84. The energy consumption from the high-pressure reservoir66is minimal by this measure.

Upon standstill of the hydraulic cylinder6then both valves84,116are closed and the check valve142is in its closing position again. The high-pressure reservoir66is thus separated from the hydraulic cylinder6. The driving element6is then reset in the afore-described manner by adjusting the reset control valve128into one of its positions marked by (a), the hydraulic medium required for resetting being supplied by the constant-displacement pump64which is now driven by the common motor. During said return motion comparatively low pressures occur in the system, the motion is moreover relatively slow so that the reset control valve128can be designed to have a comparatively small nominal size. During the decelerating phase, the resetting motion and the standstill of the hydraulic cylinder6the hydraulic reservoir66can be charged relatively slowly via the variable-displacement pump62, because sufficient time is available. During the waiting period to the next acceleration of the driving element2the driving side of the control system is practically unloaded so that no separate locking means is necessary.

In the embodiment shown inFIG. 4the flexible drive4is designed to have two pull ropes28,30, wherein two additional deflection pulleys148,150serving for deflecting a respective one of the pull ropes28or30are provided at the driving element2. This facilitates exchange of the pull ropes28or30, because they have no longer to be detached from the driving element2. In this embodiment each of the two movable sets of pulleys20,22is designed to have six pulleys44so that accordingly a six-fold transmission ratio is formed. The respective allocated set of deflection pulleys24,26is correspondingly designed, wherein the pull rope is guided such that the piston rod18is symmetrically loaded and that the two end portions of the pull ropes28,30end in the respective axial area of the piston rod16,18. The two end portions of each pull rope28,30are then anchored in this embodiment by a tension spring152,154by which the pull ropes28,30are kept tensioned. The tension springs152,154are designed such that they are adapted to transmit the necessary pulling forces to accelerate the driving element2. The rope is guided by additional stationary guide pulleys48,50,52and156.

In the above-described embodiments the flexible drive4is designed such that the movable set of pulleys20,22and the stationary set of deflection pulleys24,26are disposed in extension of the hydraulic cylinder6so that a comparatively large building space is required in axial direction. As shown inFIG. 5, the rope guiding of the flexible drive4can also be such that the rope is guided laterally from the hydraulic cylinder6. The movable set of pulleys20,22is fixed—similar to the afore-described embodiment—at a respective end of the allocated piston rod16and/or18, the individual pulleys44being arranged coaxially with respect to each other and being represented in top view. The two allocated sets of deflection pulleys24,26are then inwardly offset toward each other so that they are located on both sides of the cylinder jacket. The stationary deflection pulleys24,26can be supported on the cylinder or on the frame of the roller coaster. The two end portions of the—in this case—common pull rope28are in turn anchored in a stationary manner. The pull rope28is then guided via further guide pulleys48to the driving element2(not shown) and the latter is fixed to the pull rope28. Of course, a pull rope guiding of this type can also be performed with two pull ropes.

In the afore-described embodiments a hydraulic cylinder6is used comprising two piston rods16,18which preferably have the same diameter. On principle, instead of such an equal area cylinder also a differential cylinder having one single piston rod16, to which then the movable sets of pulleys20,22are fixed, can be employed. The two sets of deflection pulleys24,26are in turn supported in a stationary manner. The pulley arrangement is wrapped by a common pull rope28to which the driving element2is fixed. As a matter of fact, instead of the single pull rope28wrapping the entire flexible drive4also a variant having two separate pull ropes28,30according toFIG. 4can be used.

The control system illustrated especially by way ofFIG. 3permits operation of a roller coaster with minimum losses of energy, wherein the control system need not necessarily be designed in the shown complex manner, however. InFIG. 7the minimum requirements to said control system are represented. Accordingly, the flexible drive4not shown is actuated by a hydraulic cylinder6(equal area cylinder, cylinder including two piston rods, differential cylinder) by which all movements of the driving element2are controlled. The two pressure chambers10,12of the hydraulic cylinder6in the simplest case can be connected via a control valve system158to a high-pressure side HDS and/or a low-pressure side NDS. The term high-pressure side HDS is understood to be, for instance, a high-pressure reservoir66and a high-pressure pump (variable-displacement pump62). The term low-pressure side NDS basically stands for the return side to the tank T. In this area a low-pressure reservoir may be provided to compensate for pressure variations. The control valve system158may be designed by one or more control valves.

As mentioned already, the applicant reserves itself to direct a separate independent set of claims to the principle of said control system comprising the component parts shown inFIG. 7or the further embodiments according toFIG. 3.

There is disclosed a catapult drive for an object to the accelerated, preferably the car of a fairground ride, wherein the object is accelerated by means of a driving element. The movement of the driving element is produced by a flexible drive and a hydraulic cylinder via which all movements of the driving element can be controlled. There is further disclosed a control system for suitably controlling the inventive catapult drive.