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(11) | EP 3 144 069 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | MATERIAL PROCESSING APPARATUS WITH DUAL DRIVE SYSTEM |
| (57) A material processing apparatus comprising a material processing device operated
by a rotary operating device. A primary drive system is coupled to the rotary operating
device and is operable to rotate the rotary operating device. A secondary drive system
has a rotary drive member and is operable between a driving state and a non-driving
state. The apparatus is operable in a primary mode in which the primary drive system
rotates the rotary operating device or in a secondary mode in which the secondary
drive system rotates the rotary operating device. The rotary drive member is positioned
such that its rotational drive axis is co-incident with the rotational axis of the
rotary operating device.
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Field of the Invention
[0001] The present invention relates to material processing apparatus. The invention relates particularly, but not exclusively, to crushers.
Background to the Invention
[0002] The Powerscreen Premiertrak 400 (trade mark) is an example of a material processing apparatus comprising a crusher, in particular a jaw crusher. The crusher is operated by rotating a pulley, rotational movement of the pulley being translated into reciprocating movement of a jaw within the crusher. The pulley may be driven by a direct drive system that is capable of rotating the pulley in one direction only.
[0003] A typical direct drive system comprises a belt and pulley drive mechanism driven by an engine via a clutch. The engine does not include gears and is not reversible; it drives the pulley system in one direction only when the clutch is engaged. Such a drive system is desirable since, when running at normal operating speed, it is very fuel efficient. However, two problems with such systems are that it cannot undo blockages in the crusher because it does not have a reverse mode, and also that it does not operate efficiently whenever the engine is not operating at normal operating speed, e.g. during an initial start up period. In the event of a jam, the crusher must be emptied and the jammed material removed manually. The crusher must then be restarted while empty since the direct drive system is not suitable for starting under load conditions. As an alternative to the direct drive system, a hydrostatic drive system may be used that is capable of driving the pulley in either direction. This allows jams to be cleared automatically and without having to empty the crusher. However hydrostatic drives are relatively expensive and suffer from relatively poor fuel efficiency and power utilisation in comparison with the direct drive system.
Summary of the Invention
[0005] A first aspect of the invention provides a material processing apparatus comprising:
a material processing device, which may for example be a crusher;
a rotary operating device coupled to said material processing device for the operation thereof;
a primary drive system coupled to said rotary operating device and being operable to rotate said rotary operating device;
a secondary drive system having a rotary drive member, said secondary drive system being operable between a driving state, in which said rotary drive member is operable to rotate said rotary operating device, and a non-driving state in which said secondary driving system does not rotate said rotary operating device,
wherein said processing apparatus is operable in a primary mode in which said primary drive system rotates said rotary operating device and said secondary drive system is in said non-driving state, or in a secondary mode in which said secondary drive system is in said driving state and operated to rotate said rotary operating device,
and wherein said rotary drive member is positioned such that its rotational drive axis is substantially co-incident with the rotational axis of the rotary operating device.
[0006] Advantageously, said secondary drive system is operable in a neutral mode in which said rotary drive member is freely rotatable, said secondary drive system adopting said neutral mode when in said non-driving state.
[0007] Typically, aid secondary drive system comprises a motor, for example a hydraulic motor, for rotating said rotary drive member, said motor being positioned such that its rotational drive axis is substantially co-incident with the rotational axis of the rotary operating device.
[0008] In preferred embodiments the apparatus includes a control system configured to implement a start up mode in which said secondary drive system is in said driving state and said primary drive system is deactivated, and wherein in response to determining that said rotary operating device has reached a desired rotational speed, said control system is configured to cause said secondary drive system to adopt said non-driving state and to activate said primary drive system. The preferred control system is configured to cause said secondary drive system to adopt said non-driving state before said primary drive system is activated.
[0009] In typical embodiments, said primary drive system comprises a motor coupled, when the primary drive system is activated, to said rotary operating device for the rotation thereof. The rotary operating device may comprise a pulley, said motor being coupled to said pulley when the primary drive system is activated. Usually, the motor is coupled to said rotary operating device by a drive belt, the belt being driven by a pulley coupled to said motor. Typically said pulley is coupled to said motor by means of a clutch.
[0010] In preferred embodiments, the primary drive system is operable to impart rotational movement to said rotary operating device in one rotational direction only. Advantageously said secondary drive system is operable to impart rotational movement to said rotary operating device in either rotational direction.
[0011] The control system may be configured to implement a blockage clearance mode in which said secondary drive system is in said driving state and said primary drive system is deactivated, and wherein in response to determining that rotation of said rotary operating device is impeded, said control system is configured to cause said secondary drive system to rotate said rotary operating device alternately in both rotational directions.
[0012] A second aspect of the invention provides a material processing apparatus comprising:
a material processing device;
a rotary operating device coupled to said material processing device for the operation thereof;
a primary drive system coupled to said rotary operating device and being operable to rotate said rotary operating device;
a secondary drive system having a rotary drive member, said secondary drive system being operable between a driving state, in which said rotary drive member is operable to rotate said rotary operating device, and a non-driving state in which said secondary driving system does not rotate said rotary operating device; and
a control system configured to implement a start up mode in which said secondary drive system is in said driving state and said primary drive system is deactivated, and wherein in response to determining that said rotary operating device has reached a desired rotational speed, said control system is configured to cause said secondary drive system to adopt said non-driving state and to activate said primary drive system.
[0013] A third aspect of the invention provides a method of operating the material processing apparatus of the first or second aspects of the invention, the method comprising implementing a start up mode by causing said secondary drive system to adopt said driving state and deactivating said primary drive system; and in response to determining that said rotary operating device has reached a desired rotational speed, causing said secondary drive system to adopt said non-driving state and activating said primary drive system.
[0014] In preferred embodiments, the dual drive system comprises a hydraulic motor and an engine/pulley drive system. The hydraulic motor is operable in a reverse mode, for example to clear blockages in the crusher, and can also be used to start the crusher, or other apparatus, and bring it to a desired operational speed after which the engine/pulley drive system is engaged by the clutch. Advantageously, when the clutch is engaged, the crusher, or other apparatus, is already running at its operational speed, which reduces wear on the clutch.
[0015] Further advantageous features of the invention will be apparent to those ordinarily skilled in the art upon review of the following description of a specification embodiment and with reference to the accompanying drawings.
Brief Description of the Drawings
[0016] An embodiment of the invention is now described with reference to the accompanying drawings in which:
Figure 1 is a perspective view of a material processing apparatus including a dual drive system embodying one aspect of the present invention;
Figure 2 is a side view of a first side of the material processing apparatus of Figure 1;
Figure 3 is a plan view of the material processing apparatus of Figure 1;
Figure 4 is a side view of the second side, opposite the first side, of the material processing apparatus of Figure 1;
Figure 5 is a schematic view of the dual drive system embodying the invention;
Figure 6 is an exploded view of a preferred hydraulic motor mounting assembly suitable for used in the dual drive assembly;
Figure 7 is an assembled view of the mounting assembly of Figure 6;
Figure 8 is a flow chart illustrating a start up procedure; and
Figure 9 is a flow chart illustrating a blockage clearance procedure.
Detailed Description of the Drawings
[0017] Referring now to the drawings, there is shown, generally indicated as 10, a material processing apparatus. Only those parts of the apparatus that are helpful for understanding the present invention are shown. In general, the apparatus 10 may be configured to perform any one or more of a plurality of processes, such as feeding, screening, separating, crushing, waste recycling or demolition and/or washing, on one or more types of aggregate or other material, for example rocks, stones, gravel, sand and/or soil, or any other material that is quarried, mined or excavated. To this end, the apparatus may include one or more material processing device 12 configured to perform one or more of the foregoing processes. In typical embodiments of the invention, and as is illustrated, the material processing device 12 comprises a crusher. It will be understood that the invention is not limited to crushers and may be employed with other types of material processing device, in particular those that are operable by means of a rotary operating device, for example a shredding chamber.
[0018] The apparatus 10 is typically carried by a chassis 13. The chassis 13 may also carry one or more other components (not shown) that facilitate use of the crusher 12, usually a feed assembly for delivering material to the crusher 12 and one or more conveyors for transporting crushed or uncrushed material, e.g. for the purposes of stockpiling. The feed assembly may comprise a hopper and a screen. In a typical arrangement, material deposited into the hopper is graded by the screen as a result of which some of the material (usually the larger pieces that do not pass through the screen) is fed to the crusher 12 while the rest bypasses the crusher 12 and is directed elsewhere, e.g. to a conveyor.
[0019] The powered components of the apparatus 10, including the crusher 12, are typically powered by one or more hydraulic system comprising motor(s), actuator(s) and/or other component as required. It will be understood that alternative power systems, e.g. electrical or pneumatic systems, may be used, and so the motor(s) and other components may be powered by alternative means. An electrical system may also be provided as would be apparent to a skilled person. In any event the apparatus 10 includes a power plant (not shown) for generating the requisite power (e.g. including electrical, hydraulic and/or pneumatic power as applicable) for the apparatus 10. The power plant may take any convenient conventional form, e.g. comprising any one or more of an engine, compressor and/or batteries.
[0020] In typical embodiments, the apparatus 10 is mobile and comprises one or more wheels and/or tracks 11 mounted on the chassis 13. The apparatus 10 may be self-propelled and to this end the power plant 22 usually comprises an internal combustion engine (not visible). In such cases, the internal combustion engine conveniently generates power for the hydraulic system(s), e.g. by operating the hydraulic pump(s) (not shown), and may also power an electric generator (not shown) for the electrical system.
[0021] The crusher 12 includes a rotary operating device 24 that is rotatable about an axis A-A'. During use, rotation of the rotary operating device 24 about axis A-A' operates the crusher 12. In a normal operating mode, the rotary operating device 24 is rotated in one direction only, e.g. clockwise as viewed in Figure 2. In the illustrated embodiment, the crusher 12 is a jaw crusher comprising a crushing chamber 9 with a movable jaw 15 and another, typically fixed, jaw 17 between which material may be crushed. The rotary operating device 24 is coupled to the movable jaw 15 such that rotation of the device 24 causes the movable jaw 15 to move back and forth with respect to the other jaw 17 to effect a crushing action. The rotary operating device 24 typically comprises a driven pulley 26. The driven pulley 26 is mounted on a shaft 28, the shaft 28 being coupled to the movable jaw 15. Rotation of the pulley 26 rotates the shaft 28 to operate the crusher jaws. In the illustrated embodiment, a fly wheel 27 is mounted on the opposite end of the shaft 28. The shaft 28 is contained usually within a housing 30.
[0022] The apparatus 10 includes a dual drive system for operating the rotary operating device 24, the dual drive system comprising a primary drive system 32 and a secondary drive system 40.
[0023] The primary drive system 32 is coupled to the rotary operating device 24 in order to rotate the device 24 about axis A-A'. The primary drive system 32 comprises a motor 34 coupled to the device 24 by one or more drive belt 36. The motor 34 typically comprises an internal combustion engine, optionally the same engine that may be provided to drive the wheels/tracks 11. Conveniently, the drive belt(s) 36 runs around the pulley 26. The primary drive system 32 includes a second pulley 38 coupled to the motor 34. In use, the drive shaft of the motor 34 drives (rotates) the second pulley 38, which drives the belt 36, which in turn drives (rotates) the pulley 26. Typically, the motor 34 is coupled to the second pulley 38 by a clutch 39. The input side of the clutch may be mounted to the main engine drive, the output side of the clutch being connected to the drive belt(s) 36. The clutch 39 is operable to allow the engine drive to be disconnected from the output of the clutch.
[0024] In preferred embodiments, the motor 34 drives the second pulley 38 directly, i.e. without an intervening gearbox or source of torque reduction. The preferred primary drive system 32 is advantageous in that it is relatively inexpensive, robust, fuel efficient and power transfer efficient. However, it is only able to rotate the rotary operating device 24 in one direction (clockwise as viewed in Figure 2) because, in this example, the output shaft of the motor 34 is only capable of rotating in one direction and, in the absence of an intermediate gearbox or other mechanism to allow the drive direction to be reverse, the pulley 38 can only be rotated in one direction. The inability to reverse the direction of drive, means that the primary drive system 32 cannot be used to assist in clearing a blockage of the crusher 12 by driving the operating device 24 in the opposite sense (counterclockwise as viewed in Figure 2). Also, the drive system 32 is not suited to starting the crusher 12 under load.
[0025] In addition, it is preferred to use a motor 34 that is a constant speed motor, i.e. has a drive shaft that rotates at a constant rotational speed during normal operation (i.e. after start up). A problem with such motors however is that engaging them with a load at a relatively high rotational speed is very hard wearing on the clutch. It will be understood however that the invention is not limited to use with constant speed motors.
[0026] The apparatus 10 includes a secondary drive system 40 comprising a motor 60 and rotary drive member 42 that is driven (rotated) by the motor 60 in use. The rotary drive member 42 is coupled to the rotary operating device 24 for rotating the rotary operating device 24 about the axis A-A'. Advantageously, the rotary drive member 42 is positioned such that its rotational drive axis is substantially co-incident with the rotational axis A-A' of the rotary operating device 24. The motor 60 is also positioned such that its rotational drive axis is substantially co-incident with the rotational axis A-A' of the rotary operating device 24. Conveniently, this may be achieved by locating the motor 60 at either end of the rotary operating device, e.g. at one or other end of the shaft 28, or otherwise substantially on the rotational axis of the shaft 28.
[0027] In the illustrated embodiment, the motor 60 and drive member 42 are located at the opposite end of the rotary operating device 24 to the driven end, i.e. opposite the pulley 26. Conveniently, the drive member 42 is coupled to the fly wheel 27. In the illustrated embodiment, the rotary drive member 42 comprises a bracket, which may be fixed to the fly wheel 27 (or other part of the rotary operating device 24 as is convenient) by any suitable fixings, e.g. bolts. Alternatively, the motor 60 and drive member 42 may be located at the same end of the rotary operating device 24 to the driven end, i.e. adjacent and, conveniently, coupled to the pulley 26, as illustrated in broken outline in Figure 5.
[0028] In preferred embodiments, the motor 60, more particularly the motor housing, is coupled to the apparatus 10, e.g. to the chassis 13 or the (non-rotating) body of the crusher, by a support structure 61 by which the motor housing is held stationary with respect to the rotary operating device 24. The support structure preferably comprises a torque arm. The torque arm 61 preferably extends substantially perpendicularly to the rotational axis A-A'. To this end, a torque post 63 may be provided on the apparatus 10 extending laterally outwards such that part of it is level with the motor housing. The torque arm 61 is coupled to the motor housing and to the torque post 63, the torque post 63 providing a reaction point for the torque arm 61.
[0029] The secondary drive system 40 is operable in either one of a driving state, in which the rotary drive member 42 imparts rotation to the rotary operating device 24, and a non-driving state in which it does not rotate the rotary operating device 24. The motor 60 is a reversible motor, i.e. capable of rotating the drive member 42 in either direction about rotation axis A-A', at least when the secondary drive system 40 is in the driving state. Typically, the motor 60 is a hydraulic motor and may be powered by the power plant, conveniently by the motor 34. In the example of Figure 5, the motor 60 is powered by a hydraulic pump 80 that is driven by a secondary drive shaft of the motor 34. The hydraulic motor is of a type that allows the internal drive of the motor 60 to be disengaged when the secondary drive system is not in use. The motor 60 may alternatively be an electric motor, a pneumatic motor or other conventional type of motor.
[0030] In preferred embodiments, in the non-driving state the secondary drive system 40 operates in a neutral mode in which the internal rotary drive components of the motor 60 and the rotary drive member 42 are freely rotatable, i.e. not driven by the motor 60. In the illustrated embodiment, the neutral mode is effected by configuration of the hydraulic circuit that controls the motor 60, as is described in more detail below with reference to Figure 10, such that hydraulic power is not provided to the rotary drive components of the motor 60 thereby rendering them freely rotatable. In this case, both the motor 60 and the drive member 42 can freely rotate in the neutral mode.
[0031] In use, the dual drive system is operable in a primary mode in which the primary drive system 32 operates the crusher 12. To this end, the primary drive system 32 is configured such that the motor 34 drives the pulley 38, which drives the pulley 26 via the drive belt(s) 36 to rotate the rotary operating device 24. In the primary mode, the secondary drive system 40 is in its non-driving state. The dual drive system is alternatively operable in a secondary mode in which the secondary drive system 40 is in its driving state and rotates the rotary operating device 24. In the secondary mode, the secondary drive system 40 may be operated to rotate the operating device 24 alternately in both rotational directions (clock wise and counter clockwise about axis A-A') in order to facilitate clearance of material jams or blockages. Typically, the primary drive system 32 is deactivated in the secondary mode, and this may be achieved by operating the clutch 39 to disengage the motor 34 from pulley 38 to allow pulley 38 to rotate freely. Alternatively, the primary drive system 32 may be deactivated by removing the drive belt(s) 36 from the pulley 26.
[0032] The primary drive system 32 and secondary drive system 40 may be operated using any suitable control system, including in the illustrated embodiment a hydraulic control unit 70 and an electrical control unit 72, and typically also comprising a common, or a respective, user operable control panel (not shown), which may be electrical and/or hydraulic as applicable.
[0033] Referring now to Figure 5 in particular, the dual drive system includes a hydraulic control unit 70 for controlling the operation of the secondary drive system 40, in particular the motor 60. The hydraulic control unit 70 is connected to the hydraulic pump 80, which is connected to a source of hydraulic fluid (not shown). The hydraulic control unit 70 includes a hydraulic circuit (not shown) having a valve for controlling the flow of hydraulic fluid to and from the motor 60. The circuit, or at least the part of it that supplies the motor 60, may be configured as an open circuit such that, in the neutral mode, the hydraulic fluid returns to the hydraulic fluid tank without supplying hydraulic pressure to the motor 60. As such, the motor 60 can rotate freely. To this end, the valve, which may be of the type commonly referred to as an open centre valve, is operable in a mode (which is adopted during the neutral mode) in which the hydraulic fluid returns to the tank through the valve without supplying hydraulic pressure to the motor 60. In preferred embodiments, the motor 60 is of a type in which the internal drive (not shown) is disengaged in the neutral mode. It is not necessary for the motor to circulate hydraulic fluid when disengaged. In any event, the motor 60 is operable in a neutral mode in which it and the rotary drive member 42 are freely rotatable and do not drive the rotary operating device 24 even though the rotary drive member remains coupled to the rotary operating device 24.
[0034] An electrical control unit 72 is provided for controlling the electrically controllable components of the dual drive system, including the motor 34 and the clutch 39. The electrical control unit 72 may take any suitable form, e.g. electrical circuitry and/or a programmable control device such as a PLC, microprocessor or microcontroller.
[0035] Referring now to Figure 8, a preferred start up procedure for the dual drive system is described (assuming that there are no blockages in the crusher 12). Following a request (801) to start the crusher 12, the secondary drive system 40 is caused to adopt the driving state (802, 803) during which it drives the rotary operating device 24 in its normal operating direction. These steps may be user initiated using any convenient user control. At this stage, and while the secondary drive system is in the drive mode, the primary drive system 32 is initiated so that the motor 34 starts up, but remains deactivated so that power from the motor 34 is not transmitted to the rotary operating device 24, which in the present embodiment involves maintaining the clutch 39 in a disengaged state. Also while the secondary drive system 40 is in the driving state the control system monitors the speed of the rotary operating device 24 to check if it has reached a clutch engagement speed, which is preferably a speed that matches, i.e. is the same or substantially the same as, the normal operational speed of the motor 34 (804). When it is determined that the rotary operating device 24 is at the desired speed, then the secondary drive system 40 is caused to adopt the non-driving state (805). Next, the primary drive system 32 is activated to drive the rotary operating device 24 (806), which in the present embodiment involves engaging the clutch 39. Once the primary drive system 32 is active, the hydraulic power to the secondary drive system 40 can be turned off (807). In alternative embodiment, the primary drive system 32 could be started up only after the rotary operating device 24 has reach clutch engagement speed.
[0036] Figure 9 shows a preferred procedure for removing a blockage in the crusher. Following a request (901) to remove a blockage, the secondary drive system 40 is caused to adopt the driving state (902, 903) during which it drives, or attempts to drive, the rotary operating device 24 in a first rotational direction. These steps may be user initiated using any convenient user control. The control system, or the user, checks if the blockage has cleared (904). This may for example be achieved by determining if the rotary operating device 24 is rotating in the intended driven direction. If it is determined that the blockage is still present, then the secondary drive system 40 is operated to rotate the rotary operating device 24 in the opposite direction (905), following which step 904 is repeated. When it is established that the blockage is cleared, the secondary drive system 40 is deactivated, which typically involves turning off the power to the motor 60 (906) and causing the secondary drive system 40 to adopt the non-driving state (907).
[0037] It will be apparent that the operation of the dual drive system, including the procedures outlined above with reference to Figures 9 and 10, may be controlled by the electrical and/or hydraulic control units 70, 72 as appropriate, each of which may take any suitable form.
[0038] The control system may be configured to implement an interlock such that the secondary drive system 40 cannot be operated into its driving state when the primary drive system 32 is driving the crusher 12. For example the control system may be configured such that the secondary drive system 40 cannot be operated into its driving state until the motor 34 has been disengaged from the pulley 38.
[0039] It will be apparent from the foregoing that preferred embodiments of the invention provide the efficiency of a clutch driven drive system with the functionality of a hydraulic drive system. Advantageously, the secondary drive system is used to accelerate the rotary operating device 24 to near operating speed then the clutch 39 can be engaged and the hydraulic motor disengaged. The hydraulic motor can also be used to start the crusher 12 when it is blocked. To do this the hydraulic motor can rotate the crushing chamber forward and backwards to free blocked material.
1. A material processing apparatus comprising:
a material processing device;
a rotary operating device coupled to said material processing device for the operation thereof;
a primary drive system coupled to said rotary operating device and being operable to rotate said rotary operating device;
a secondary drive system having a rotary drive member, said secondary drive system being operable between a driving state, in which said rotary drive member is operable to rotate said rotary operating device, and a non-driving state in which said secondary driving system does not rotate said rotary operating device,
wherein said processing apparatus is operable in a primary mode in which said primary drive system rotates said rotary operating device and said secondary drive system is in said non-driving state, or in a secondary mode in which said secondary drive system is in said driving state and operated to rotate said rotary operating device,
and wherein said rotary drive member is positioned such that its rotational drive axis is substantially co-incident with the rotational axis of the rotary operating device.
2. The apparatus of claim 1 wherein said secondary drive system is operable in a neutral
mode in which said rotary drive member is freely rotatable, said secondary drive system
adopting said neutral mode when in said non-driving state.
3. The apparatus of claim 1 or 2, wherein said secondary drive system comprises a motor
for rotating said rotary drive member, said motor being positioned such that its rotational
drive axis is substantially co-incident with the rotational axis of the rotary operating
device, said motor preferably being located at either end of the rotary operating
device.
4. The apparatus of Claim 3, wherein said motor comprises a hydraulic motor, said motor
advantageously being operated by a hydraulic circuit configurable to allow said motor
to rotate freely.
5. The apparatus of any preceding claim wherein, in said secondary mode, said primary
drive system is deactivated.
6. The apparatus of any preceding claim wherein, in said non-driving state, said rotary
drive member is freely rotatable with respect to said rotary operating device.
7. The apparatus of claim 3, wherein, in said non-driving state, said motor is freely
rotatable with respect to said rotary operating device.
8. The apparatus of any preceding claim, further comprising a control system configured
to implement a start up mode in which said secondary drive system is in said driving
state and said primary drive system is deactivated, and wherein in response to determining
that said rotary operating device has reached a desired rotational speed, said control
system is configured to cause said secondary drive system to adopt said non-driving
state and to activate said primary drive system, and wherein said control system is
preferably configured to cause said secondary drive system to adopt said non-driving
state before said primary drive system is activated.
9. The apparatus of any preceding claim, wherein said primary drive system comprises
a motor coupled, when the primary drive system is activated, to said rotary operating
device for the rotation thereof, said rotary operating device optionally comprising
a pulley, said motor being coupled to said pulley when the primary drive system is
activated, and wherein, optionally, said primary drive system motor is coupled to
said rotary operating device by a drive belt, the belt being driven by a pulley coupled
to said primary drive system motor, and wherein, optionally, the pulley is coupled
to said motor by means of a clutch, said motor preferably driving said pulley directly
in use.
10. The apparatus of any preceding claim, wherein said primary drive system is operable
to impart rotational movement to said rotary operating device in one rotational direction
only.
11. The apparatus of any preceding claim, wherein said secondary drive system is operable
to impart rotational movement to said rotary operating device in either rotational
direction, and wherein said secondary drive system motor is preferably capable of
rotating said drive member in either rotational direction about its rotational axis.
12. The apparatus of claim 11, further comprising a control system configured to implement
a blockage clearance mode in which said secondary drive system is in said driving
state and said primary drive system is deactivated, and wherein in response to determining
that rotation of said rotary operating device is impeded, said control system is configured
to cause said secondary drive system to rotate said rotary operating device alternately
in both rotational directions.
13. The apparatus of any preceding claim wherein said primary drive system comprises a
constant speed motor.
14. The apparatus of any one of claims 3 to 13, wherein the motor of the secondary drive
system is coupled to the apparatus by a support structure by which the motor housing
is held stationary with respect to the rotary operating device, and wherein the support
structure preferably comprises a torque arm.
15. The apparatus of any preceding claim, wherein said material processing device comprises
a crusher, typically a jaw type crusher.