Abstract:
A portable nutcracker includes a handle member and a retaining member which are fittable together and axially adjustable with respect to one another. The nutcracker includes a battery powered motor which drives an epicyclic outputting to a threaded shaft on which a ram travels linearly toward and away from an anvil on the retaining member. As a safety feature, the ram advances only when the power button is activated, and retracts automatically when the power button is released. As a power-saving feature, the nutcracker automatically powers down when the ram reaches its forward or backward limit of motion. Faster action may be achieved by adjusting the retaining member relative to the handle member to decrease the space between the ram and the anvil prior to activating the motor.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates to improved technology in the field of nutcrackers and more particularly to a hand-held, portable nutcracker which is motorized to enable a user to safely break open the shells of a variety of shapes and sizes of nuts using minimal strength and effort. 
       BACKGROUND OF THE INVENTION  
       [0002]    Numerous kinds of portable nutcrackers are conventionally available. Portability in a nutcracker is desirable for several reasons, the most notable of which is portability. Portability is important to those who sample before buying and those who are picknicking. Where a market vendor&#39;s permission is obtained beforehand, it may be beneficial for a buyer to crack open and sample different kinds of nuts prior to purchasing large quantities. 
         [0003]    Conventional nutcrackers which are manually actuated may use leverage to transmit the power necessary to crack the shell of a nut. Similarly, conventional manual nutcrackers may utilize a threaded screw to convert hand-turning motion into axial motion to break the shell. Many other kinds of cam-action devices are commonly used in manually operated nutcrackers to convert mechanical input into the power needed to crack a nutshell. 
         [0004]    Conventional manually-actuated nutcrackers are convenient because of their portability, but almost all manual nutcrackers require a high degree of strength for effective operation. Some manual nutcrackers require availability of a level surface on which to place the nutcracker for stability and ease of operation. Handles which may be used to actuate conventional manual nutcrackers may be easily broken off while trying to crack a tough-shelled nut because the amount of force necessary to crack the nut may exceed the strength of material of the handle. 
         [0005]    Conversely, some manually-actuated devices consistently over-amplify the input energy so that both the nutshell and the nut kernel are often unintentionally crushed. Consequently, the kernel may be pulverized and rendered inedible. Often, unintentional crushing occurs sporadically, and variation in technique may not helpful in correcting the problem because the power mechanism may be cyclic or may be otherwise beyond the control of a user. This is highly undesirable in general, and especially so where exotic or costly nuts are at risk. 
         [0006]    Conventional motorized nutcrackers are also available, but many of these are not portable because they require an AC power source for operation. Plug-in type motorized nutcrackers limit a user&#39;s location where they may operate the nutcracker. Many people prefer to crack nuts out-of-doors because cracking nuts usually results in scattering a certain amount of shell shards. Users who do not have access to outdoor AC power may be forced to crack their nuts inside, where clean-up is usually more difficult because of carpeting, for example. Additionally, shell shards which are overlooked after clean-up may cause injury to humans and pets if stepped on with bare feet, a situation which is more likely to occur where nuts have been shelled indoors. 
         [0007]    A user who wishes to shell nuts outdoors using a plug-in type nutcracker may, of course, purchase an extension cord which can be connected from an AC power outlet indoors to an optimal outside location. However, this is likely to be inconvenient, may waste energy where a window or door must be used to pass the cord from indoors to outdoors, and could even be quite costly where an extraordinarily long drop cord is necessary. 
         [0008]    Other conventionally available motorized nutcrackers are touted as portable because they lack power cords and do not require AC power for operation. Many of these, however, may be large in size to accommodate internal components capable of transmitting enough force to crack a nut. Likewise, they may be designed as heavy machines to minimize vibrational effects. While technically portable, these devices may be so large, heavy, or cumbersome that they are inconvenient to carry from place to place and are therefore not truly practical as portable devices. 
         [0009]    Many conventionally available nutcrackers, whether manual or motorized, may present serious dangers to the user. Cyclic nutcrackers, which generally do not permit interruption by a user once activated, are potentially injurious if fingers or other objects become caught in the crushing mechanism. Spring-action nutcrackers can also result in blunt trauma or may cause shell shards to project through the air, potentially causing eye or other injury. Where projectiles are a possibility, a user may not be able to avoid injury even with safety glasses or other preventive safety measures. Finally, some manually operable nutcrackers have freely-moving parts which may dislodge during use to cause injury to a user. 
         [0010]    What is therefore needed is a powerful, hand-held, manually-actuatable, motorized nutcracker which is both safe and easily controllable by a user. The optimal nutcracker may be used to successfully break open nutshells of a variety of thicknesses with only minimal effort by a user. The ideal nutcracker has a self-contained power source, is easily portable, and may be used virtually anywhere at any time, without regard to location or the strength of a user. 
       SUMMARY OF THE INVENTION  
       [0011]    The nutcracker of the present invention may include a handle member and an retaining member. The retaining member may be fitted and screwed onto the handle member, ideally using helical threads. The end of the handle member which is engageable with the retaining member and may include a ram which is movable toward and away from an anvil on the retaining member when the handle member and the retaining member are connected. The helical threads allow the retaining member to be axially adjustable relative to the handle member so that the space between the ram and the anvil may be varied by a user to accommodate different sizes of nuts. 
         [0012]    The handle member may include a motor which is optimally powered by batteries, allowing the nutcracker to be completely self-contained and portable. The motor may drive an epicyclic (or planetary) drive train. When the motor is activated, energy may be input from the motor into the epicyclic drive train via a shaft which may connect the motor to a central or “sun” gear. As the sun gear rotates, it may turn a plurality of planetary gears. The planetary gears may be attached to a planet carrier such that the planet carrier rotates in the same direction as that of the sun gear during operation. Multiple stages of planetary gears may be compounded together to increase the overall gear ratio in a compact form. 
         [0013]    A threaded output shaft may be attached to the planet carrier and may engage with a corresponding set of threads in the ram. As the planet carrier rotates, the output shaft rotates such that the ram moves linearly backward and forward along the output shaft. The direction of movement of the ram depends on the direction of rotation of the output shaft. Optimally, the range of ram movement should be about 35 mm to allow for cracking a variety of nut sizes and shapes. The ram may include a chock to prevent the ram from rotating with the output shaft when the nutcracker is being operated. 
         [0014]    The movement of the ram in the present invention is ideally slow and controlled, thereby giving a user increased control over the ram and decreasing the possibility of user injury by impingement or by shell projectiles. Where faster nut-cracking action is desired, a user may adjust the retaining member relative to the handle member so that the ram contacts and lightly secures the nut in position against the anvil. The user may then activate the motor to cause the ram to advance toward the anvil to crack the nut. This arrangement may increase the efficiency of nut-cracking, especially where there are large numbers of nuts to be shelled, because it eliminates the travel time necessary for the ram to move from a fully retracted position to a position of light contact with the nut. Thus, the time required for cracking each nut will only be attributable to the time it takes the ram to advance from a point of light contact with the nut to a point at which the nut cracks, a distance which may roughly approximate about 4 mm, on average. Additionally, a user may be able to conserve power while cracking a thin-shelled nut by merely adjusting the handle member relative to the retaining member without activating the ram. 
         [0015]    The epicyclic drive train may include a ring gear which may act as a slipping clutch to limit the amount of torque that can be delivered to the output shaft. The ring gear may be fixed during operation under a normal load, but will optimally begin to slip when too much torque occurs to prevent overloading the motor and other components. 
         [0016]    The handle member may include a double-pole, double-throw (DPDT) switch for reversing the polarity of the motor so that the direction of movement of the ram may be controlled. The travel of the ram may be limited in either direction either by (1) a cam switch which may be activated when the ram is fully extended or fully retracted, or by (2) manual interruption of the motor circuit via the DPDT switch. 
         [0017]    Ideally, the DPDT switch may have an ON position and an OFF position. When a power button on the nutcracker is activated, the DPDT switch is turned ON and adjusts the polarity of the motor so that the ram moves toward the anvil. When maximum forward movement of the ram has been reached, a transfer rod, which may be connected between the ram and the switch cam, may cause the switch cam to interrupt power to the motor to stop the ram from further advancing. Whenever the ram is not fully advanced, the user may cause the ram to automatically retract by simply releasing the power button to reverse the polarity of the motor and activate backward motion of the ram. 
         [0018]    In the OFF position, which may be achieved by releasing the power button, the DPDT reverses the polarity of the motor so that the ram is retracted away from the anvil. Once the ram is fully retracted, the transfer rod may be used to interrupt power to the motor to stop the ram from further retracting (based on the same cam switch mechanism explained in the preceding paragraph). Additionally, if the unit has been powered down by the cam switch while the ram is in the fully extended position, the power button may simply be released to allow the ram to retract automatically. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]    The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
           [0020]      FIG. 1  is a perspective view of the nutcracker of the present invention as disassembled into a handle member and an retaining member; 
           [0021]      FIG. 2  is a perspective view of the front end of the nutcracker of  FIG. 1  as assembled and illustrates a ram extending through one end of the handle member and oppositely disposed from an anvil in the retaining member; 
           [0022]      FIG. 3  is a side view of the nutcracker of the present invention wherein the retaining member has been axially advanced onto the handle member to narrow the gap between the anvil and the ram; 
           [0023]      FIG. 4  is a partial cutaway view of the handle member of the nutcracker of the present invention which more clearly illustrates the mechanisms by which the nutcracker operates; 
           [0024]      FIG. 5  is a view of the switching mechanism as attached to the ram via a transfer rod; 
           [0025]      FIG. 6  is a block diagram which illustrates a possible configuration of the components in the nutcracker; 
           [0026]      FIG. 7  is a simplified schematic illustrating an analog realization of the operation of the nut cracker and is shown with the switches in an orientation ready for initiation of the cracking process and also at the maximum reverse limit; 
           [0027]      FIG. 8  is a simplified schematic as seen in  FIG. 7  and shown with the switches in a position which would be occupied upon some forward advance of the ram; 
           [0028]      FIG. 9  is a simplified schematic as seen in  FIGS. 7 &amp; 8  and shown with the switches in a position which would be occupied at the most forward extent of the advance of the ram, at the moment that the forward limit switch is opened; 
           [0029]      FIG. 10  is a simplified schematic as seen in  FIGS. 7-9  and shown with the switches in a position which would be had during retraction of the ram and before the reverse limit is reached at which time the reverse limit switch would be opened as shown in  FIG. 7 ; 
           [0030]      FIG. 11  is a bottom view of one realization of the cam switches seen in  FIG. 5 ; 
           [0031]      FIG. 12  is a bottom view of the switches seen in  FIG. 5  which operate against the bottom view of the cam switches seen in  FIG. 11 ; 
           [0032]      FIG. 13  is a plan view of a further embodiment of a nut cracker having a unitary body and eye loop anvil support; 
           [0033]      FIG. 14  is a plan view of a further embodiment of a nut cracker having a unitary body and an anvil support having an open side; and 
           [0034]      FIG. 15  is a plan view of one possible realization of a slip clutch utilizable with the nutcracker embodiments shown herein. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]    The description and operation of the invention will be best initiated with reference to  FIG. 1 , which is a perspective view of a nutcracker  11 .  FIG. 1  illustrates nutcracker  11  as having a handle member  13  and a retaining member  15 . Handle member  13  has a first end  17  and a second end  19 . A ram  21  is shown fully extended through first end  17  of handle member  13 . Handle member  13  includes an abbreviated helical thread  23  adjacent first end  17 . Situated between first end  17  and second end  19  is a power button  25 . Second end  19  of handle member  13  includes a removable cap  27 . 
         [0036]    Retaining member  15  of nutcracker  11  includes a cylinder  29  and a loop  31 . Loop  31  has an inner surface  33  to which an anvil  35  is mounted. Anvil  35  may be secured to loop  31  using fasteners  37 . Loop  31  terminates in an opening  39  opposite anvil  35  through which the interior surface  41  of cylinder  29  is visible. The interior surface  41  of cylinder  29  includes a helical thread  43  which is compatible with the helical thread  23  on first end  17  of handle member  13 . The inside diameter of cylinder  29  is slightly larger than the outside diameter of first end  17  of the handle member  13  so that the cylinder  29  of retaining member  15  can be passed onto first end  17  of handle member  13  and helical thread  23  of handle member  13  can be engaged with helical thread  43  on the interior surface  41  of cylinder  29 . 
         [0037]    Retaining member  15  may be axially adjusted to any of a range of positions along first end  17  of handle member  13  to vary the space between ram  21  and anvil  35 . Given that the travel of ram  21  may be limited, the adjustability of the retaining member  15  relative to the handle member  13  effectively expands the size range of nuts that may be successfully cracked using the nutcracker  11 . Although nutcracker  11  is illustrated in  FIG. 1  as having a generally cylindrical shape, nutcracker  11  can be any number of different sizes or shapes which allow the retaining member  15  to be adjustably connected to handle member  13 . 
         [0038]      FIG. 2  is a perspective view of the front end of the nutcracker  11  of  FIG. 1  as assembled.  FIG. 2  illustrates the handle member  13 , including removable cap  27  and power button  25 , and the retaining member  15  attached to first end  17  of handle member  13  at cylinder  29 . Further illustrated in  FIG. 2  is loop  31 , including anvil  35  and fasteners  37 . Through opening  39  in loop  31 , first end  17  of handle member  13  is visible, including ram  21 , which is fully retracted and flush with first end  17  of handle member  13  in  FIG. 2 . 
         [0039]    When a nut (not illustrated) is placed inside loop  31  and power button  25  is depressed, ram  21  advances toward anvil  35  to crack the nut. Again, given that the travel of ram  21  may be limited, a user may, where small nuts are to be cracked, adjust retaining member  15  by screwing it further onto first end  17  of handle member  13  so that the space between ram  21  and anvil  35  is decreased. This allows even small varieties of nuts to be successfully cracked using the nutcracker  11 . 
         [0040]    Furthermore, where sizeable but thin-shelled nuts are to be cracked, a nut may be placed inside loop  31 , and retaining member  15  may be adjusted downward onto handle member  13  so that the nut is pressed between ram  21  and anvil  35 . By continuing to advance retaining member  15  onto handle member  13 , the nut may be cracked without depressing power button  25 , and thus the use of power may be reserved for smaller nuts (where fully advancing retaining member  15  onto handle member  13  may not produce sufficient pressure to crack the nut) and/or tougher nuts (where motorized power may be necessary to break the nutshell). 
         [0041]      FIG. 3  is a side view of the nutcracker  11  of  FIG. 2  and illustrates the retaining member  15  connected to the handle member  13  and axially advanced onto handle member  13  so that the space between anvil  35  and ram  21  is narrowed.  FIG. 3  further illustrates removable cap  27  and power button  25  of handle member  13 , as well as the inner surface  33  of loop  31 . The ram  21  is illustrated as partially extended in  FIG. 3 . 
         [0042]      FIG. 4  is a partial cutaway view of the handle member  13  of the nutcracker  11  which more clearly illustrates the mechanisms by which the nutcracker  11  operates. Nutcracker  11  is illustrated as having a motor  45  which may be powered by a battery pack  47 . Battery pack  47  may be accessed through removable cap  27  at second end  19  of handle member  13 . Because nutcracker  11  is a hand-held unit that is compact in size and optimally relies only on battery power, nutcracker  11  is truly portable and can be carried and used virtually anywhere. Power button  25  controls a switch  49  which is optimally a double-pole, double-throw (DPDT) switch capable of reversing the polarity of the motor  45  especially in an analog realization. 
         [0043]    Motor  45  has an output shaft  51  which may drive an epicyclic drive train  53  located in a gearbox  55 . The epicyclic gear train may be singular or a compound of multiple stages. Output shaft  51  ideally drives a central or “sun” gear  57  which, in turn, drives a plurality of planetary gears  59 . Planetary gears  59  may be mounted to a planet carrier  61 . Epicyclic drive train  53  may further include a ring gear  63 . Ring gear  63  is optimally fixed relative to the inner wall of gearbox  55  but may include a clutch mechanism whereby high levels of torque allow the ring gear  63  to slip relative to gearbox  55  to minimize wear and damage. Alternatively, a slipping clutch may be placed between two epicyclic stages allowing the input sun gear on the second stage to slip relative to the output carrier of the first stage. 
         [0044]    If motor  45  rotates output shaft  51  clockwise, planetary gears  59  optimally rotate counter-clockwise. If the ring gear  63  is fixed, the rotation of planetary gears  59  causes the planetary gears  59  to revolve inside the ring gear  63  in a clockwise direction, thus rotating planet carrier  61  in a clockwise direction. If a high degree of torque occurs, a clutch mechanism will allow the ring gear  63  to slip and thus be rotated by the planetary gears  59 . As a result, planet carrier  61  will stop rotating, which may help to avoid overloading the motor  45 , or avoid stopping the mechanism for example. 
         [0045]    Although ring gear  63  is illustrated here as occupying only a component of gearbox  55 , it is conceivable that the entire interior of gearbox  55  could act as a ring gear and a clutch mechanism could be located between gearbox  55  and the interior wall of handle member  13 . The arrangement illustrated in  FIG. 4 , however, may generate the least amount friction. A thrust bearing  65  may be included adjacent planet carrier  61  and may act to absorb axial load pressure to protect the epicyclic drive train  53  from being distorted, among other things. 
         [0046]    A threaded output shaft  67  is illustrated as attached to planet carrier  61 . Ram  21  is shown engaged with threaded output shaft  67  and is illustrated as including a chock  69  to keep ram  21  from rotating with threaded output shaft  67 . As a result, when threaded output shaft  67  rotates in a given direction, ram  21  advances or retracts axially along threaded output shaft  67  such that the position of ram  21  varies between full retraction (wherein ram  21  is flush with first end  17  of handle member  13 ) and full extension (wherein ram  21  extends fully through first end  17  of handle member  13  up to chock  69 . Again, given that the range of travel of ram  21  may be limited as described, a user would ideally have the option to adjust retaining member  15  relative to handle member  13  when necessary to accommodate small nuts or to conserve power while cracking thin-shelled nuts or to avoid smashing. 
         [0047]      FIG. 4  further illustrates a transfer rod  71 , which may extend between ram  21  and a circuit board  73 , to which DPDT switch  49  and battery pack  47  are also connected. A cam switch  75 , including an actuator  77  which operates upon switches  79  and  81  supported by the circuit board  73 . The cam switch  75  may be interposed between transfer rod  71  and circuit board  73  for powering down the nutcracker  11  when the ram  21  has reached either a forward or backward limit of movement. 
         [0048]      FIG. 5  is an isolated view which more clearly illustrates the relationship between ram  21  (including chock  69 ), transfer rod  71 , and cam switch  75 . Also illustrated in  FIG. 5  is DPDT switch  49  as connected to circuit board  73 . 
         [0049]      FIG. 6  is a block diagram which illustrates one potential configuration of the components inside nutcracker  11 . In this configuration, DPDT switch  49  may be activated using power button  25 , not illustrated in  FIG. 6 . Activating DPDT switch  49  turns nutcracker  11  on and activates CONTROL CIRCUITRY PROCESSOR  85 . CONTROL CIRCUITRY PROCESSOR  85  can activate motor  45 , which activates the epicyclic drive train  53 , causing ram  21  to move forward. At the circuit level, forward movement of ram  21  might occur by the opening of a backward motion circuit, which is normally closed, and by the closing a forward motion circuit, which is normally open, so that power is delivered from the battery  47  to the motor  45 . 
         [0050]    When ram  21  reaches its forward limit of motion, transfer rod  71  activates a cam switch  85  to override the DPDT switch  49  and interrupt power to motor  45  so that ram  21  is halted and is prevented from further forward motion. Following the circuit-level example from above, cam switch  85  may re-open the forward motion circuit that was previously closed by activating the DPDT switch  49 . Ram  21  is also prevented from backward motion while the power button  25  is being depressed (again, based on the circuit-level example, the backward motion circuit should remain open as long as the DPDT switch  49  is activated). 
         [0051]    If power button  25  is released so that the DPDT switch  49  is deactivated, CONTROL CIRCUITRY PROCESSOR  85  changes the polarity of motor  45  so that ram  21  is retracted. At the circuit level, this may occur via an opening of the forward motion circuit and a closing of the backward motion circuit. As ram  21  reaches its backward limit of motion, transfer rod  71  again acts on the cam switch  77  to interrupt power to motor  45  so that ram  21  is halted and is prevented from further backward motion. Continuing to follow the circuit-level example, cam switch  77  may re-open the backward motion circuit which was previously closed by deactivating the DPDT switch  49 . Ram  21  is also prevented from forward motion because the power button  25  is not being depressed (and based on the circuit-level example, the forward motion circuit should remain open when the DPDT switch  49  is not activated). A dashed control line between cam switch  75  and DPDT switch  49  is seen where the control circuitry processor  77  is minimal or absent, and where the cam switch  75  can control the operation directly by manipulating the DPDT switch  49 . 
         [0052]    In this configuration, ram  21  moves toward anvil  35  to crack a nut when power button  25  is manually depressed. When ram  21  reaches its forward limit, the nutcracker  11  turns off automatically to conserve power and to avoid undue wear on the motor  45  and other components. Because an appreciable amount of space remains between ram  21  and anvil  35  even where retaining member  15  is completely advanced onto handle member  13  and ram  21  is fully extended, the possibility of pinching injury is lessened. The space between ram  21  and anvil  35  is further preserved by the built in power-off function of the nutcracker  11 . As an added safety feature, ram  21  will advance only when the power button  25  is depressed, and release of power button  25  automatically and fully retracts ram  21  and powers down nutcracker  11 . This makes the nutcracker  11  both intuitive and safe to use. 
         [0053]    In an analog embodiment the cam switch  75  can operate with a switch  49  as a double pole double throw switch. Referring to  FIG. 7  a battery is connected to a double pole double thrown switch  49  which can switch the positive pole of the battery to either direct current input of a motor M. In  FIG. 7 , the switch  49  is shown in its unactuated position. A reverse limit switch RL is shown in the open position, and a forward limit FL switch is shown in the closed position. In any position between a forward limit and a reverse limit, both the forward and reverse limit switches would be closed. 
         [0054]    Thus,  FIG. 7  illustrates a position where the ram is in its rearward most position, in which the user is ready to use the nut cracker  11 . In this position positive power which would otherwise pass through reverse limit switch RL is interrupted and the nut cracker  11  is at rest. Upon actuation of the nut cracker  11 , the user depresses switch  49  which introduces positive power into the motor M, with a return negative connection through the forward limit switch FL which has remained closed both while the nut cracker  11  is at rest and just after the ram  21  starts forward. 
         [0055]    Referring to  FIG. 8 , this condition is shown. As can be seen both the Reverse limit switch RL and the forward limit switch FL are closed. The user continues to hold the switch  49  down to drive the ram  21  forward to cause the nut to be cracked. In this mid ram position, it can be seen that if the user were to inadvertently let go of switch  49 , that the positive power would be introduced into the negative terminal of the motor M and it would reverse its direction and continue to reverse its direction until the reverse limit switch opened as was shown in  FIG. 8 . 
         [0056]    However, in normal use, the user will continue to press the button  49  until the nut is cracked. If the user keeps the button  49  depressed at the forward limit, and if there were no forward limit switch, the motor would continue to turn. If a slip clutch were present, it would continue to slip and wear. In effect, a forward limit switch, with the presence of a slip clutch is to protect the slip clutch from excessive wear. Where a forward limit switch is present, the analog schematic for achievement of the forward limit is shown in  FIG. 9 , where the forward limit switch FL achieves an open circuit. The configuration seen in  FIG. 9  is one where the user continues to press the switch  49 , the ram  21  has traveled to its forward most extent and the forward limit switch FL is open. As can be seen, the circuit between the battery and motor is interrupted and the motor stops. Note that the reverse limit switch RL remains closed. 
         [0057]    Referring to  FIG. 10 , a circuit schematic is shown at the point where the user releases the button  49 . The battery positive terminal is connected to the negative terminal of the motor M, and the ram  21  moves rearwardly. In effect, the nut cracker  11  goes into reverse even if it is put down or placed on a table by a user. The ram  21  continues in reverse until the ram reaches its rearward limit where the reverse limit switch RL opens. This state is shown in  FIG. 7  and represents the reset state where the nut cracker  11  is again ready to be forward actuated to crack a nut. 
         [0058]    Referring to  FIG. 11 , a closeup view of cam switch  81  illustrates one possible configuration in which cammed surfaces can be arranged. A first raised surface  91  has a lowered surface  93  which presents itself to an open-on-release forward limit switch. At the other side of the cam switch  81 , a second raised surface  95  has a lowered surface  97  which presents itself to an open-on-release reverse limit switch. The transfer rod  71  may have additional mechanisms which enable sliding “play” with regard to the cam switch  81 . Referring to  FIG. 12  the bottom mechanisms of the switches  79  and  81  are seem to have projecting switch elements  101  and  103 , respectively. 
         [0059]    Given the path over which the ram  21  must travel, the utilization of the axial adjustable feature of the retaining member  15  can be eliminated if the path of travel of the ram  21  were to be arranged with a longer stroke. A longer stroke would mean more running time for a given pitch of ram  21  driving thread, and a longer return time, but the need for manual adjustability would be eliminated. Referring to  FIG. 13 , a further embodiment of a nut cracker is seen as a nut cracker  111 . Nut cracker  111  includes a single piece housing  113 . The ram  115  has a curved surface, and operated against an anvil  117  having a similarly matched curved surface. The design of the nut cracker  111  is such that the extent of travel of the ram  115  toward the anvil  117  can be limited, both by the internals of the device, as well as the curvatures of the ram  115  and anvil  117 . The ram  115  and the anvil  117  operated within a closed eye loop structure  119  and the nuts can be loaded from either side of the eye loop. 
         [0060]    Referring to  FIG. 14  a further embodiment is seen as a nut cracker  121 , with the major difference taken with respect to nut cracker  111  of  FIG. 13  being the provision of an opening  123  on one side of a structure supporting the anvil  117  with respect to the ram  115 . A further reinforcement of a connection arm  125  will be necessary to bear the forces occurring between the anvil  117  and the ram  115 . The opening  123  enables a better view of the cracking operation and enables a more direct manipulation of a nut between the anvil  117  and the ram  115 . 
         [0061]    Referring to  FIG. 15 , a plan view of one embodiment of a slip clutch assembly  131  is seen which can be used with the nutcracker  11 ,  111  or  121  of the invention, as well as other uses. A housing  135  may be a sprocket or a planetary gear carrier or may have its other components operated by a planetary gear carrier such as carrier  61 . Inside the housing  135  an internal space  137  having a series of concentric scalloped surfaces  139  is shown. Inside the space a fitting includes two half annular sections  143  each having an outwardly projecting engagement cam  145  which may be at a center of each of the two half annular sections  143 . The two half annular sections  143  each engaged a scallop surface  139  directly in front of it. The two half annular sections  143  may join around a common ring  147  and may support a raised pinion gear  149  to either take or input gear power. The housing  135  may have teeth  151  either take or input gear power, especially in conjunction with pinion gear  149 . Any force differential between the housing  135 , especially from the gear teeth  151 , and the includes two half annular sections  143 , especially from the pinion gear  149 , which exceeds the engagement of the outwardly projecting engagement cam  145  with the scallop surfaces  139  directly in front of it will cause the outwardly projecting engagement cam  145  to disengage with the scallop surface  139  directly in front of it and jump to the next most adjacent scallop surface  139 . This will occur with an audible “click” noise to give an instant notification to the user that the force being put through the slip clutch has exceeded its threshold clutch value. The slip clutch assembly  131  will continue to click and slip until the power is reversed or until the obstacle preventing further action of the ram  21  is removed. The shape and orientation of the outwardly projecting engagement cam  145  with the scallop surfaces  139  is such that slippage may repeatedly occur without any significant wear or diminution of threshold value of the slip clutch assembly  131 . 
         [0062]    Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.