Abstract:
A warning system is disclosed for use on a concrete mixer to indicate that a charge hopper  28  is in a raised position. Such concrete mixers include an air supply, a mixing drum having an access port, a frame supporting the mixing drum, and a charge hopper  28  that is pivotally supported adjacent the access port. The charge hopper  28  is moveable between a raised position and a lowered position. The warning system includes an indicator device  70  operatively associated with the concrete mixer and configured for activation to indicate when the charge hopper is in the raised position. A valve  44  is operatively associated with the frame and in fluid communication with the air supply  14  and the indicator device  70 . The valve  44  includes an actuator moveable between a first position to deactivate the indicator device and a second position to activate the indicator device. A contact structure  50  is operatively associated with the charge hopper to actuate the valve.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention relates generally to a warning system for a charge hopper, and, more particularly, to a warning system for use on mobile-type concrete mixers to signal the operators thereof when the concrete mixers&#39; charge hoppers are in a raised position. 
     2. Background of the Related Art 
     Mobile-type concrete mixers are the workhorse in the building industry. There are tens-of-thousands of such concrete mixers in operation today throughout the world. Their basic function is to mix and deliver tons of concrete to a variety of settings including residential and industrial construction sites. Mobile-type concrete mixers can be classified into two groups—tractor-carried concrete mixers and tractor-drawn concrete mixers. 
     The tractor-carried concrete mixers have two basic configurations. They include a conventional configuration which is loaded and delivers concrete from the rear of the vehicle and a front-loader configuration which, as the name implies, is loaded and delivers concrete from the front of the vehicle. Although configured differently, they share similar characteristics. That is, they each include a cab for the operator to drive the vehicle, an air supply system, a mixing drum, frames to support the mixing drum, a charge hopper, and controls for operating the mixing drum and charge hopper. 
     Tractor-drawn concrete mixers basically comprise a trailer-mounted concrete mixer that is pulled by a tractor. They tend to have a larger capacity then tractor-carried concrete mixers and are often used for large pours such as found in highway and dam construction. Although configured somewhat differently then the tractor-carried concrete mixers, tractor-drawn concrete mixers share similar characteristics. That is, they include a cab in the tractor for the operator to drive the vehicle, an air supply system, a mixing drum, frames to support the mixing drum, a charge hopper, and controls for operating the mixing drum and charge hopper. 
     Both tractor-carried concrete mixers and tractor-drawn concrete mixers may alternatively be referred to simply as concrete mixers. To simplify the description of the present invention, reference will be made only to tractor-carried cement mixers. Those skilled in the art will appreciate that the present invention will benefit any and all types of mobile-type concrete mixers. 
     Referring to FIGS. 1 and 2, a perspective view of a conventional tractor-carried concrete mixer designated by reference numeral  10  and an elevational view of a rear portion of the concrete mixer  10  are illustrated, respectively. In the descriptions provided herein below, like reference numerals identify similar structural elements. 
     As noted above, a tractor-carried concrete mixer  10  includes a cab  12  that provides a protective enclosure in which the operator drives the truck and controls various functions of the concrete mixer. Concrete mixer  10  also includes an air supply system that provides compressed air for actuating a breaking system, for actuating pneumatic cylinders, and for general-purpose usage. The air supply system includes a compressor that is driven by the tractor&#39;s engine and charges a volume tank  14  to store compressed air for the above-described purposes. 
     Concrete mixer  10  further includes a mixing drum  16  for mixing and storing cement, aggregate, and water, i.e., concrete. The mixing drum  16  has a closed end and an open end. The open end is an access port  18  through which cement, aggregate, and water are poured into the interior of the mixing drum  16  and out of which concrete is poured. 
     The controls  19  are typically located within eyeshot of the access port  18  to enable an operator to manipulate the controls  19  while observing delivery of concrete from the mixing drum  16 . The type and number of controls  19  vary from concrete mixer to concrete mixer. However, all concrete mixers include a control to operate the mixing drum  16 , and to raise and lower the charge hopper as described in more detail herein below. 
     The mixing drum  16  is rotationally supported by a set of frames including a cab-side frame  20  and a hopper-side frame  22 . The cab-side frame  20  supports the closed end of the mixing drum  16  through a tapered roller bearing (not shown). The hopper-side frame  22  supports the open end of the mixing drum  16  through a pair of rollers (not shown) that ride against a support ring  24  attached to the mixing drum  16 . Extending from the upper portion of the hopper-side frame  22  is a near-side vertical support  26  and a complementary far-side vertical support (not shown). 
     The charge hopper  28  is funnel-shaped and is utilized in a lowered position to guide cement, aggregate, and water from storage containers at a concrete plant, through the access port  18 , and into the mixing drum  16 . The charge hopper  28 , when moved to a raised position, allows concrete to pour unobstructed from the mixing drum  16 , out through the access port  18 , down a chute attachment  30  (shown in its stored position), and into, for example a pour frame. 
     The near-side vertical support  26  and far-side vertical support provide mounting points for the charge hopper  28 . More specifically, the charge hopper  28  is pivotally mounted by a near-side pivot pin  32  to a near-side attachment arm  34  which is attached to the near-side vertical support  26 , and a complementary far-side pivot pin to a far-side attachment arm (not shown) which is attached to the far-side vertical support. 
     A first end  38  of a pneumatic lift cylinder  36  is mounted to the near-side vertical support  26  and a second end  40  is mounted to the charge hopper  28  for pivoting the charge hopper  28  between the lowered position and the raised position. That is, the charge hopper  28  is pivoted from the lowered position to the raised position by extending the pneumatic lift cylinder  36 , thereby pivoting the charge hopper  28  in the counter-clockwise direction about the pivot pins as indicated by the “Y” arrow (FIGS.  1  and  3 ). The charge hopper  28  is pivoted from the raised position to the lowered position by retracting the pneumatic lift cylinder  36 , thereby pivoting the charge hopper  28  in the clockwise direction about the pivot pins as indicated by the “X” arrow (FIGS.  1  and  2 ). The charge hopper  28 , illustrated in FIGS. 1 and 3. is shown in the raised position while the charge hopper  28  illustrated in FIG. 2 is shown in the lowered position. Although the lift cylinder  36  is described herein as a “pneumatic” lift cylinder, such lift cylinders might also be hydraulically operated. 
     Those skilled in the art will appreciate that when the charge hopper  28  is in the raised position it increases the overall height of the tractor-carried concrete mixer  10  by approximately one to two feet. Therefore, proper operation of the concrete mixer  10  dictates that the charge hopper  28  should be located in the lowered position any time the vehicle is traveling over roadways; thereby preventing it from accidentally hitting low overpasses, power cables, light poles, etc., and causing severe property damage and personal injury. However, due to a wide variety of distractions found at construction sites, it is relatively easy for an operator to forget that the charge hopper is in the raised position. 
     It would be beneficial to provide a system to warn an operator of a tractor-carried concrete mixer or tractor-drawn concrete mixer that the charge hopper is in the raised position. Such a system should be relatively inexpensive, easy to install, operate and maintain. 
     SUMMARY OF THE INVENTION 
     The subject invention is directed to a warning system for use on a concrete mixer that includes an air supply, a mixing drum having an access port, and a charge hopper pivotally supported adjacent the access port, wherein the charge hopper is mounted for movement between a raised position and a lowered position. 
     An embodiment of the warning system includes an indicator device operatively associated with the concrete mixer and configured to be activated to indicate when the charge hopper is in the raised position. A valve is operatively associated with the concrete mixer and in communication with the air supply and the indicator device. The valve includes an actuator moveable between a first position to deactivate the indicator device and a second position to activate the indicator device. A contact structure is operatively associated with the charge hopper to actuate the valve. In use, pressurized air is transmitted from the air supply to the indicator device when the actuator of the valve is in the first position. The indicator device may be a diaphragm-type indicator having a warning arm that pivots into the field of vision of an operator when it is activated. 
     Another embodiment of the present invention includes a kit for mounting on a concrete mixer to indicate when a charge hopper is in a raised position. The kit includes at least one conduit, an indicator device configured to be activated to indicate when the charge hopper is in the raised position, a valve configured to communicate with an air supply and the indicator device through the at least one conduit, wherein the valve includes an actuator moveable between a first position to deactivate the indicator device and a second position to activate the indicator device, and a contact structure configured to actuate the valve. The kit may be packaged in any type of packaging available on the market. For example, the packaging may be a box with formed inserts to support its contents. 
     Another embodiment of the present invention includes a method for indicating when a charge hopper is in a raised position on a concrete mixer. Preferably, the method includes the step of providing an indicator device operatively associated with the concrete mixer and a valve operatively associated with the concrete mixer and in communication with an air supply and the indicator device, the valve including an actuator moveable between a first position to deactivate the indicator device and a second position to activate the indicator device. The method further includes the steps of pivoting the charge hopper to the raised position, actuating the valve to move the actuator from the first position to the second position, and activating the indicator device to indicate the charge hopper is in the raised position. 
     These and other unique features of the present invention generally described as a warning system for a charge hopper will become more readily apparent from the following drawings and description thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that those of ordinary skill in the art to which the subject invention appertains will more readily understand how to make and use the invention described herein, preferred embodiments of the invention will be described in detail herein below with reference to the drawings wherein: 
     FIG. 1 is a perspective view of a tractor-carried concrete mixer having a charge hopper in a raised position; 
     FIG. 2 is a side elevational view of a rear portion of a tractor-carried concrete mixer that includes an embodiment of the present invention; 
     FIG. 3 is a side elevational view of a rear portion of a tractor-carried concrete mixer that includes an embodiment of the present invention; 
     FIG. 4 is a schematic view of a two-position, three-port valve used in an embodiment of the present invention; 
     FIG. 5 is a side elevational view in cross section of a low-pressure indicator, 
     FIG. 6 is a side elevational view in cross section of an alternate type of indicator; 
     FIG. 7 is a schematic view of a two-position, three-port valve used in an embodiment of the present invention; and 
     FIG. 8 is a perspective view of a kit for marketing an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As described above in reference to FIGS. 1-3, a typical tractor-carried concrete mixer  10  includes a cab  12  for an operator to drive the vehicle, an air supply system, a mixing drum  16 , a set of frames  20  and  22  to support the mixing drum  16 , and a charge hopper  28 . The charge hopper  28  is moved to a lowered position so cement, aggregate, and water may be poured into the upper portion of the charge hopper  28  as shown by arrow “Z” (FIG.  2 ), funneled through the access port  18 , and dumped into the mixing drum  16 . The charge hopper  28  is moved to a raised position to allow concrete to pour unobstructed from the mixing drum  16 , down a chute attachment  30  (shown in its stored position), and poured into, for example, a pour frame. 
     Referring in particular to FIGS. 2 and 3. an embodiment of the present invention is illustrated. The embodiment is assembled to the tractor-carried concrete mixer  10 . A detailed description of the embodiment follows herein below. As noted above, although the description provided herein and the figures referred to concern a tractor-carried concrete mixer, the present invention may be utilized on any mobile-type concrete mixer. 
     A mounting bracket  42  is mounted to the near-side attachment arm  34 . A valve  44  is mounted to the mounting bracket  42  with its actuator  46  facing upward. The valve  44  can alternatively be described as a switching device. The mounting bracket  42  may be made adjustable with respect to the near-side attachment arm  34 , for example, by including slots in the mounting bracket  42  and using screws to secure it in place. In addition, the valve  44  may be made adjustable with respect to the mounting bracket  42 , for example, by including slots in the mounting bracket  42  and using screws to secure the valve  44  in place. It is notable that the mounting bracket  42  and valve  44  may in the alternative be mounted to the charge hopper  28 . Circumstances relating to a particular installation will dictate the most preferable mounting location. 
     Referring to FIG. 4, as illustrated schematically, the valve  44  is a plunger actuated, two-position, three-port type pneumatic valve. The three ports are identified as port “A”, port “B”, and port “C”. In position 1, wherein the plunger is depressed, an air passage is formed between port “A” and port “B”. In position 2, wherein the plunger is released to allow a spring to act within the valve, an air passage is formed between port “B” and port “C”. Those skilled in the art will appreciate that other types of valves may be used in the present embodiment without departing from the breath and scope of the invention. 
     Referring again to FIGS. 2 and 3, a supply conduit  48  provides fluid communication between the volume tank  14  and port “A” of the valve  44 . The supply conduit  48  may be made of rigid tubing, flexible tubing, or a combination of both. Circumstances relating to a particular installation will dictate the most preferable types of materials to use. 
     A contact structure  50  is mounted to the charge hopper  28 . The contact structure  50  may be made adjustable with respect to the charge hopper  28 , for example, by including slots in the contact structure  50  and using screws to secure it in place. The contact structure  50  is positioned on the charge hopper  28  so that it depresses the plunger actuator  46  when the charge hopper  28  is in the lowered position (FIG. 2) and releases the plunger actuator  46  when the charge hopper  28  is in the raised position (FIG.  3 ). The term “raised position” shall be interpreted broadly to include any position other than the lowered position. 
     It is notable that if the mounting bracket  42  and valve  44  are mounted to the charge hopper  28  as described above, then the contact structure  50  would be mounted to, for example, the near side attachment arm  34  so that it will function to actuate the plunger actuator  46  as described above. It is also notable that the contact structure  50  may be configured to actuate any type of actuator  46  available such as a lever actuator, magnetic actuator, etc. If, for example the actuator is a magnetic actuator, then the contact structure  50  may simply be a portion of the charge hopper  28  which has magnetic properties sufficient to activate the valve  44 . 
     A low-pressure indicator  52  (“L.P. indicator”) is mounted to the tractor-carried concrete mixer  10  in a location that is conspicuous to the operator when he is preparing to move the vehicle. The L.P. indicator is a diaphragm-type indicator. Generally, regardless of the particular configuration, indicators are considered to be “activated” when they signal an operator that the charge hopper is in the raised position, and “deactivated” when the signal is removed or disabled. The L.P. indicator  52  includes an inlet connector  54  for attaching a conduit. Although in most cases it may be preferable to locate the L.P. indicator  52  in the cab  12 , under certain circumstances it may be preferable to locate it, for example, near the driver&#39;s-side door handle of the cab  12  or near the concrete mixer controls  19  (FIG.  1 ). 
     A signal conduit  56  provides fluid communication between port “B” of the valve  44  and the inlet connector  54 . The signal conduit  56  may be made of rigid tubing, flexible tubing, or a combination of both. Circumstances relating to a particular installation will dictate the most preferable types of materials to be used. 
     Referring to FIG. 5, the L.P. indicator  52  is shown to include an upper housing  58  and a lower housing  60 . A cavity  62  is formed there between. An air channel  64  extends between the inlet connector  54  and the cavity  62 . A diaphragm  66  is sandwiched between the upper housing  58  and lower housing  60 , thereby dividing the cavity  62  into an upper chamber  61  and a lower chamber  63 . A pin  68  extends from the diaphragm and through the lower housing  60 . A warning arm  70  is pivotally mounted by a dowel  72  to the lower housing  60  at a point proximate the pin  68 . The warning arm  70  includes a detent  74  that aligns with the pin  68  when the warning arm  70  is in the raised position as shown. 
     The pin  68  engages the detent  74  when air pressure is applied via the signal conduit  56  and air channel  64  to the upper chamber  61  of the cavity  62 . The pin  68  disengages the detent  74  when air pressure is removed from the upper chamber  61  of the cavity  62 . At such time, the warning arm  70  swings down in counter-clockwise direction as illustrated by arrow “S” to the lowered position (shown in dotted lines). An L.P. indicator that may be used in the present embodiment is the Wig-Wag® low air pressure indicator (part no. 900-0202) manufactured by Stemco Manufacturing Company (Longview, Tex.). 
     Referring to FIG. 6, an alternate type of indicator  76  is illustrated. The indicator  76  is similar to the L.P. indicator  52 , however, it includes a spring  78  in upper chamber  61  for biasing the diaphragm  66  and the pin  68  downwardly to engage the detent  74 . In addition, the indicator  76  does not include the air channel  64 , but instead includes an air channel  80  for emitting air pressure from the signal conduit  56  to the lower chamber  63 . When air pressure is emitted to lower chamber  63 . the diaphragm  66  and the pin  68  are urged upwardly to disengage the pin  68  from the detent  74  and allow the warning arm  70  to drop down to the lower position. Those skilled in the art will appreciate that other types of pressure sensitive indicators may be used in the present embodiment without departing from the breath and scope of the invention. 
     Referring to FIG. 7, a schematic for a valve  82  that may be used with the alternate type of indicator  76  is illustrated. The valve  82  is a plunger actuated, two-position, three-port type pneumatic valve. The three ports are identified as port “A”, port “B”, and port “C”. In position 1, wherein the plunger is depressed, an air passage is formed between port “B” and port “C”. In position 2, wherein the plunger is released to allow a spring to act within the valve, an air passage is formed between port “A” and port “B”. 
     Referring to FIGS. 1-5, in operation, an operator of the tractor-carried concrete mixer  10  prepares to deliver concrete to a construction site. The tractor-carried concrete mixer  10  includes an embodiment of the present invention. The embodiment utilizes indicator  52  and valve  44 . 
     In preparation, the volume tank  14  is charged with air pressure and the charge hopper  28  is moved to the lowered position. While the charge hopper  28  pivots clockwise to the lowered position as indicated by arrow “X” in FIGS. 1 and 2, the contact structure  50  contacts and depresses the plunger actuator  46  of valve  44 . At such time, the valve  44  is switched from position 2 to position 1 (FIG. 4) and pressurized air is provided from volume tank  14  through supply conduit  48 , valve  44 , signal conduit  56 , and to L.P. indicator  52 . With pressurized air applied to L.P. indicator  52 , the diaphragm  66  extends the pin  68  downward. The operator then swings the warning arm  70  up into the raised position so that the pin  68  engages the detent  74  and maintains the warning arm  70  in the raised position as illustrated in FIGS. 2 and 5. The operator is then certain that the charge hopper  28  is in the lowered position and that he can safely travel to the construction site. 
     After arriving at the construction site, but before pouring the concrete, the operator raises the charge hopper  28  utilizing the controls at the control panel  19 . While the charge hopper  28  pivots counter-clockwise to the raised position as indicated by arrow “Y” in FIGS. 1 and 3, the contact structure  50  releases the plunger actuator  46  of valve  44 . At such time, the valve  44  is switched from position 1 to position 2, the pressurized air from supply conduit  48  is closed off at port “A”, and the pressurized air in the L.P. indicator  52  and the signal conduit  56  is bled off through port “C” of valve  44 . With pressurized air removed from the L.P. indicator  52 , the diaphragm  66  moves upwardly to disengage the pin  68  from the detent  74 . The warning arm  70  then swings downward in the counter-clockwise direction (as illustrated by arrow “S”) to the lowered position as illustrated in FIGS. 3 and 5. 
     When the operator has finished pouring concrete and he is ready to leave the construction site, he may in haste jump into the cab  12  of the tractor-carried concrete mixer  10  without lowering the charge hopper  28 . As noted above, traveling over roadways with the charge hopper  28  in the raised position can cause severe property damage and personal injury. Assuming, for example, that the L.P. indicator  52  is installed in a position in the cab  12  so that the warning arm  70  is in the operator&#39;s forward field of vision when it is in the lowered position, the operator will immediately recognize that the charge hopper  28  is still in the raised position. At such time, the operator returns to the control panel  19  and lowers the charge hopper  28 . After the charge hopper  28  is lowered, the operator returns to the cab  12 , raises the warning arm  70 , and safely leaves the construction site. 
     To utilize the present invention on tractor-drawn concrete mixers, some modifications to the above-described system may be required. For example, in the case where an L.P. indicator  52  is located in the tractor&#39;s cab or near the driver&#39;s-side door, a quick-disconnect connector may be included in the signal conduit  56  so that the conduit  56  may be separated when the trailer is unhitched from the tractor. 
     Referring to FIG. 8, an embodiment of the present invention is illustrated as part of a kit  84 . The kit  84  is a convenient way in which embodiments of the present invention may be marketed. Included in the kit  84  is the L.P. indicator  52 , mounting bracket  42 , valve  44 , supply and signal conduit  48  and  56 , contactor structure  50 , and associated hardware  86 . The kit  84  may be packaged as follows. The contents of the kit  84  are positioned on a base board  88  and sealed in position with a clear plastic overlay  90  utilizing vacuum-packing methods that are well known in the art. Of course, those skilled in the art will recognize the numerous other packaging systems that may be used to package the contents, for example, boxes with inserts, plastic or paper bags, etc. 
     In view of the above, it is clear that the above-described system may be used to warn an operator that a charge hopper of a concrete mixer is in the raised position. It is also clear that the system is relatively inexpensive and easy to install on new or used tractor-carried concrete mixers. Furthermore, it is clear that the system is easy to operate and maintain. 
     While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as defined by the appended claims. It is noted that 35 U.S.C. § 112, paragraph 6, is not intended to be invoked unless a claim appended hereto, or otherwise added, specifically includes “means for” terminology.