Abstract:
An residual feed pick-up system for poultry farming utilizes a tractor and trailer combination in which the blower for a pneumatic conveyor is mounted on the trailer. The hydraulic motor that drives the blower is also located on the trailer. Feed pick-up can be effected by the trailer accompanied by a standard over-the-road tractor equipped with a conventional and economically available hydraulic power takeoff unit commonly known as a PTO. The feed supplier to the poultry farm can use any of such commonly configured tractors in its normal operating fleet combined with the trailer having the onboard hydraulically driven blower for low-volume, residual feed pick-up service, thereby increasing reliability and availability of the service at advantageously low cost.

Description:
[0001]    This application claims benefit of U.S. provisional patent application No. 60/759,414 filed Jan. 17, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to bulk transfer of material via tank trailers between storage locations. More specifically it pertains to bulk transfer of granular poultry feed from numerous satellite storage tanks to a central supply depot using tank trailers equipped with hydraulically driven pneumatic conveyors. 
       BACKGROUND OF THE INVENTION 
       [0003]    Large scale poultry farming involves raising vast numbers of birds, typically in a flock of thousands, living communally in fixed structure shelters, (“houses”). The flock remains together and does not move from a single house during nearly its entire growing cycle extending from the age of young chicks until harvesting as adults. Feeding the animals is, of course, a critical aspect of the operation and it can involve the transfer of very large quantities of food. 
         [0004]    The industry typically utilizes granular feed which the grower purchases in bulk from a feed supplier. The feed is delivered to the farm and is deposited by the supplier into one or more on-site storage bins local to the poultry houses. From time to time, as feed is dispensed to the birds from the local bins, it is replenished by the supplier. During the growing cycle, the birds require different feed formulations that correspond with their stage of maturity and further depend on other factors determined by the grower. Accordingly, the composition of the feed delivered by the supplier will change during the growing cycle. 
         [0005]    Normally at harvest time, mature birds are removed to a processing plant leaving the formerly occupied house vacant. The house is then prepared for occupancy by a new crop of young birds. Frequently there is a residual quantity of adult formulation feed in the bins of the recently vacated houses. This feed is not suitable for the incoming chicks. The grower calls on the supplier to remove residual food from the bins. The grower gets a refund for returned feed and the bins are emptied so they may be re-stocked appropriately. 
         [0006]    Feed is usually transported in bulk transfer cargo trailers equipped with large tanks and pulled by standard over-the-road tractors. The supplier ordinarily maintains a fleet of tractor-trailer combinations of size appropriate for delivery of feed to the grower-customers. Picking up residual feed from vacated poultry houses is a necessary but usually smaller volume aspect of the supplier&#39;s business. Normally only a small portion of the supplier&#39;s fleet consists of specialized tractors and trailers dedicated to residual feed pick up service. 
         [0007]    Traditionally trailers of the pick-up fleet basically have a tank for accepting the residual feed, a pick-up conveyor system for loading the residual feed to the top of the tank and another discharge conveyor system for unloading the feed from the bottom of the tank. The trailer has no loading or unloading drive power source of its own to motivate the pickup and discharge conveyor systems. 
         [0008]    A specially equipped tractor is dedicated to pick-up trailer service. In addition to its normal operating equipment, the special tractor has a blower to provide pneumatic conveying air for the pick-up conveyor system of the trailer. This tractor also has an added mechanical drive for the blower. The mechanical drive takes power from the drive transmission of the tractor&#39;s main engine. Thus the step of removing residual feed calls for bringing a trailer to the site with a specially equipped tractor, running the tractor engine to operate the blower, and transferring the residual feed from the bin to the trailer tank with the pneumatic conveyor using air provided by the tractor-mounted blower. 
         [0009]    This conventional feed pick-up system has commercially significant drawbacks. Firstly, existing tractors with pick-up capability are more expensive to outfit than standard tractors. The blower must be driven by the mechanical link to the tractor transmission. Therefore at least one tractor of the fleet must have a transmission specially equipped with the mechanical link. This can contributes substantially to the cost of the tractor because the mechanical link is an specially added tractor feature. Additionally, the supplier has to inventory special replacement parts and to undertake specialized maintenance procedures to keep pick-up service capable tractors in good repair. 
         [0010]    Secondly, conventional feed pick-up vehicles create certain logistical problems for the supplier. Feed suppliers prefer to have a low number of specially equipped pick-up service tractors. This is because these tractors are more expensive than standard tractors and the relatively low volume of feed pick-up service compared to normal feed delivery service does not justify having more than a few, minimally essential units in the fleet. However, pick-ups can occur at difficult to predict times and must meet the needs of the growers&#39; schedules. Consequently the supplier prefers to have a pick-up tractor/trailer combination available at nearly all times. The high availability is frequently satisfied by dedicating at least one tractor/trailer combination exclusively to residual feed pick-up despite the low volume of use. This can lead to suppliers overextending the time in service of the pick-up capable tractors which tends to induce more frequent unexpected breakdowns of aging equipment. In short, it is logistically difficult and relatively expensive for the feed supplier to maintain its part of the fleet of vehicles exclusively dedicated to residual feed pick-up service. 
         [0011]    Another flaw of many conventional feed pick-up fleet systems is that a rubber belt coupling is commonly included in the link between the tractor engine transmission and the blower. The coupling produces a stepped up shaft rotation speed to properly operate the blower. Accidentally from time to time either mechanical failure or operator error can cause the pneumatic conveyor transfer lines on the pick-up trailer to occlude with feed particles. The tractor transmission will continue to turn with the blower dead-headed against the plug. Unless the operator reacts quickly, damage to the blower can result. Usually the rubber belt overheats and breaks. The cost of the broken belt is not trivial, but perhaps more problematic is the expense due to time required to access and replace the broken belt with a new one. 
         [0012]    It is desirable to have an residual feed pick-up fleet system that uses more, if not all, standardized mechanical components and is logistically more flexible to operate. A system in which the supplier can use any unit of its normal tractor fleet to operate a feed pick-up trailer would be a great productivity advantage. It is also desired to have a system that has fewer special parts to stock and requires less specially trained mechanics to maintain in good operating condition. A system that is less costly to purchase, maintain, repair and operate than conventional residual feed pick-up subsystems is much desired. 
       SUMMARY OF THE INVENTION 
       [0013]    The residual feed pick-up system of this invention utilizes a trailer that includes a blower for the pneumatic conveyor mounted on the trailer rather than the tractor. Additionally, the technique for motivating the blower is hydraulic rather than mechanical. Thus feed pick-up service provided by the novel trailer avoids the operational expense of having to provide a customized, very costly tractor dedicated exclusively for pick-up service. Also, because hydraulic power operates the trailer-mounted blower, a hydraulic power supply unit which is usually a standard feature or very common accessory of many commercial over-the-road tractors can be utilized to drive the blower without radical vehicle customization. Moreover, bulk feed delivery tractors which pull cargo tank trailers of poultry feed to growers usually already have hydraulic power supply units that energize auxiliary trailer equipment such as unloading screw conveyors and s as will be explained in greater detail, below. Indeed, according to this invention the pick-up trailer can be built or easily modified such that a single tractor-mounted hydraulic power supply unit alone can operate all of the trailer-mounted hydraulically-energized equipment including the blower. Still further, the existing hydraulic power supply unit on typical poultry feed delivery service tractors should be capable of operating the novel pick-up trailer without significant modification. Hence, it is likely that many, if not all, of the tractors in a feed supplier&#39;s fleet will be suitable to work with either delivery service trailers or the novel trailer for residual feed pick-up service, thereby increasing reliability and availability of supply and pick-up services while lowering cost. 
         [0014]    Accordingly, the present invention provides a mobile transfer system for a flowable bulk material, the system comprising a mobile cargo trailer comprising (a) a towing connector for removably hitching the trailer to a tractor, (b) a tank which is effective to hold an amount of the bulk material, (c) a pneumatic pick-up conveyor operative to move bulk material into the tank from a source separate from the trailer, (d) a blower mounted on the trailer, the blower being operative to provide a conveying flow of air to the pneumatic pick-up conveyor, and (e) a hydraulically driven motor mounted on the trailer and close coupled to the blower such that the motor drives the conveyor. 
         [0015]    This invention also provides a method of transferring a flowable bulk material from a source location to a destination location comprising the steps of (a) providing at least one mobile cargo trailer comprising, a tank, a pneumatic pick-up conveyor, a blower for the conveyor, a hydraulically driven motor to operate the blower, and at least one self-propelled tractor comprising a hydraulic power takeoff unit, (b) hitching the trailer to the tractor, (c) connecting hydraulic fluid hoses from the hydraulic power takeoff unit on the tractor to the hydraulically driven motor on the trailer, (d) drawing the trailer by the tractor near to the source location, (e) energizing the hydraulic power takeoff unit on the tractor, (f) activating the hydraulically driven motor on the trailer with hydraulic fluid flowing through the hydraulic fluid hoses from the hydraulic power takeoff unit thereby operating the blower on the trailer, and (g) circulating air from the blower through the pneumatic pick-up conveyor, thereby transferring the bulk material with the conveyor from the source location to the tank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0016]      FIG. 1  is a schematic diagram of a conventional residual feed pick-up tractor and trailer of the prior art. 
           [0017]      FIG. 2  is a schematic diagram of an embodiment of an residual feed pick-up system according to this invention. 
           [0018]      FIG. 3  is a schematic diagram of hydraulic fluid flow of an residual feed pick-up system according to this invention. 
           [0019]      FIG. 4  is a schematic diagram of the hydraulic fluid flow routing of a pre-existing bulk feed delivery trailer retro-fitted with a hydraulically driven blower according to an embodiment of this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    The present invention can be understood by comparison to a typical conventional residual feed pick-up system according to the prior art illustrated in  FIG. 1 . This system includes an over-the-road tractor  2  shown coupled by hitch  5  to a mobile cargo trailer  4  on which is positioned a tank  6  intended to receive and contain for transport residual feed picked up from a poultry farm. The residual feed is to be removed from storage bin  7 . The feed is taken from the bin by blower  15  via transfer line  12 . Direction of material flow in the drawings is shown by arrows. Blower  15  is mounted on tractor  2 . 
         [0021]    As illustrated, the residual feed in bin  7  awaits picking up. Normally while the poultry house is occupied by birds, the feed from this bin is gravity fed to solids conveyor  9 . This conveyor typically includes an elongated screw rotating in a long, narrow trough. The screw is usually driven by an electric motor. The feed  21  is thus moved into the poultry house where it feeds the birds. The bin, motor and solids conveyor are permanent, stationary facilities of the poultry farm. 
         [0022]    When the residual feed is to be taken away, an operator opens an access door of the screw conveyor intake chamber  10  allowing the feed to pour out of the bin in a pile on an adjacent pad or into a convenient open container such as a bucket. Running the tractor engine to operate the blower, suction is created in transfer line  12 . This line commonly has flexible hose  13  typically about 20 ft. long and optionally terminates with a rigid hollow wand  11  of about 3-6 ft. of length. The operator places the tip of the wand into the pile of feed which pulls feed particles into the transfer line by vacuum action. 
         [0023]    The feed particles and carrier air in the transfer line  12  under vacuum are drawn into a conventional cyclone separator  14 . This separator is typically mounted at the rear end of the trailer. The solid feed particles drop to the conical section of the separator and the substantially pellet-free air flows back to the blower inlet through transfer line  16 . Prior to entering the blower, the returning air passes through a filter  17  to protect the blower from damage by entrained feed or other solid contaminants. Pressurized air flows out of the blower discharge and returns to the trailer via line  19  and is used to convey the feed particles from the cyclone separator to the tank of the trailer. Because the blower transfer lines  16  and  19  extend between the tractor and the trailer, it is customary to provide fittings in these lines to facilitate their disconnection and reconnection so that the trailer can be separated from the tractor when desired. In the traditional system the tractor is usually dedicated to working with the pick-up trailer and therefore it is relatively infrequent to need to disconnect the blower transfer lines provided that the lines are sufficiently flexible to allow the trailer to pivot about the hitch  5  as it is drawn behind the tractor. 
         [0024]    The pellets fall from the separator into a substantially pressure-sealing, rotary feed valve  20  sometimes called an “air lock” for reasons now to be explained. The rotary feed valve has a cylindrical case with an elongated, vaned impeller. The impeller is caused to rotate at an adjustable speed. Particles drop into the upward facing compartments of the impeller between vanes and travel downward through the feeder as the impeller rotates. They then fall into line  19  and are transported to the top of the trailer tank by pneumatic conveyor line  22 . A pressure tight seal is maintained between the tips of the vanes and the interior wall of the case. The rotary feed valve thus provides an air lock interface between the negative pressure (vacuum) on the cyclone side of the rotary feed valve and the positive pressure of the pneumatic conveyor line on the blower discharge side. 
         [0025]    The picked-up feed moves through a horizontal conduit  24  inside the top of the trailer tank, which is therefore shown in phantom lines. Pick-up feed cargo tanks  6  are typically divided into multiple compartments within the tank shell. Only one such representative compartment  25  is illustrated in the figures. Conduit  24  is positioned above the compartments such that the feed particles can drop into the compartments below. The operator manipulates controls (not shown) from outside the tank to open or close valves (e.g.,  26 ) in the conduit to select the compartments to be filled by the incoming particles. 
         [0026]    The trailer also typically has mechanical functional conveyors to discharge the picked-up feed from the trailer at the supplier&#39;s storage area or other destination. The common system of discharge conveyors depicted in  FIG. 1  includes a horizontal bottom conveyor  23  disposed under the trailer tank compartments such that the operator can manipulate controls to open or close valves (e.g.,  28 ) and thereby feed by gravity particles from selected compartments into the bottom conveyor. The bottom conveyor has an internal screw-type impeller that rotates about its central axis under motivation by motor  27 . The rotating screw moves particles toward the rear of the trailer where they can flow into a vertical conveyor  33 . A rotating screw-type impeller moves the particles upward to the head of the vertical conveyor which joins boom  39 . The boom also contains a screw-type impeller that can convey the particles from the head to the discharge end of the boom. Screws of the vertical conveyor  33  and the boom  39  are both motivated in common by a single conveyor motor  36 . Vertical conveyor  33  is able to rotate about its central axis  18  and the boom  39  can pivot about a horizontal axis at its particle inlet end near the head. The combination of independent vertical conveyor rotation and boom pivoting permits the operator to position the discharge end of the boom at any angular direction  41  from 0 to 360 degrees about axis  18  and at any elevation direction  42  in a mechanical design range within the range of 0 to 180 degrees (i.e., vertically downward to vertically upward). Such rotation and pivoting permit the largely unrestricted deployment of the boom discharge near the feed ports of storage tanks located in proximity to the tank trailer at the unloading destination. Motors for rotating and elevating the boom are not shown in the drawings and operator controls are provided at a convenient station on the side of the trailer. 
         [0027]    The conventional blower  15  is motivated by the tractor engine drive train. Most of these components are within the tractor body and are therefore shown in phantom. The tractor engine  3  is equipped with a standard motor vehicle drive transmission  8 . A drive shaft  1  transmits energy to the tractor wheels in the traditional manner. Feed pick-up trailers are customized to include a second, special shaft  30  which is mechanically coupled to blower  15 . The coupling can be a direct drive with a gear box or other conventional style.  FIG. 1  schematically illustrates shaft  30  operating a drive  31  for a belt positioned within belt housing  32 . The belt operates on a sheave coaxial on a shaft with an impeller of blower  15  causing the impeller to rotate and move air through the blower. 
         [0028]    Tractor  2  is additionally equipped with a hydraulic power takeoff unit,  35  occasionally referred to as a “PTO”. Such apparatus will be discussed in greater detail below. Briefly by way of introduction, a PTO provides a flow of pressurized hydraulic liquid that can be used to activate various hydraulically fluid-driven auxiliary devices. In this case, the PTO of the conventional feed pick-up tractor is supplies pressurized hydraulic fluid to operate the bottom, vertical and boom conveyor screws, the rotation and elevation motors for the vertical conveyor and boom and the rotary feed valve impeller. Transfer lines of hydraulic fluid for these auxiliary service functions are shown at the PTO and leading to and from the trailer symbolically by lines  37 ,  38 . 
         [0029]      FIG. 1  further illustrates that hydraulic PTO  35  is powered by the tractor main engine  3  and transmission  8  via a separate and dedicated linkage such as drive shaft  34 . Thus the traditionally equipped pick-up service tractor requires two auxiliary drive shafts in addition to the wheel axle drive shaft  1 , namely, a drive shaft  30  for blower  15  and a drive shaft  34  for the PTO. A disadvantage of this configuration are that there is congestion at the connections of the two auxiliary drive shafts to the transmission. Also there is installed on the tractor an hydraulic PTO  35  capable of providing pressurized hydraulic fluid to actuate a blower. Consequently, as will be soon more fully described, there is usually no need to provide to a standard, PTO-equipped tractor an additional PTO unit to power the trailer-mounted blower called for by this invention. 
         [0030]      FIG. 2  illustrates an embodiment of the novel residual feed pick-up system according to the present invention. In the figures, the same elements have identical reference numbers. In the novel system, blower  40  is mounted on a base  43  on trailer  4 . Accordingly, the blower discharge transfer line  49  is an integral part of the trailer. For this reason, the need to disconnect the blower from the rotary feed valve  20  should be less frequent than in the conventional system and there is reduced need for a disconnection fitting in this section of the line. Of course, for maintenance purposes one or more optional disconnect fittings can be included. Similarly the blower suction transfer line  46  is part of the trailer and does not need to be disconnected and reconnected under normal circumstances except perhaps for routine maintenance. 
         [0031]    Another major distinguishing feature of the novel system is that blower  40  is operated by a hydraulic motor  47  coupled to the blower by linkage  48 . Preferably the hydraulic motor  47  is mounted on trailer  4  and more preferably it is close to the blower and positioned on the base  43 . By the term “hydraulic motor” is meant a power transmission device that converts hydraulic fluid power, i.e., hydraulic liquid, usually an oil, flowing at pre-selected flowrate and pressure, to mechanical power. Preferably the output of the motor is a rotating shaft (linkage  48 ) that turns the impeller(s) of the blower. Thus the hydraulic motor  47  preferably is supplied by hydraulic fluid via inlet hoses represented schematically by element  44 . Spent hydraulic fluid discharges from the hydraulic motor via an outlet hose  45 . 
         [0032]    Energy for motivating the hydraulic fluid through inlet and outlet hoses is generated by a hydraulic power takeoff unit  35 . Significantly, the hydraulic PTO is mounted on the tractor. Moreover, the same PTO as is normally used on tractor  2  to provide hydraulic power to operate the rotary feed valve  20  and the mechanical conveyors can be used to drive blower  40 .  FIG. 2  shows schematically that hydraulic fluid supplied by power takeoff unit  35  exits this unit via nozzle  54  and returns vi nozzle  55 . These nozzles connect to the trailer preferably by way of flexible hoses  52  and  53 , respectively. The flexible hoses can attach to trailer  4  at fittings  57  and  58  through which they connect to trailer-mounted, blower hydraulic supply and discharge lines  44  and  45 . In view that the hydraulic PTO is on the tractor and the hydraulic drive is located on the trailer, it is contemplated that operation of the residual feed pick-up system very efficiently will involve disconnecting a particular tractor from the trailer from time to time. Hence it is desirable to have disconnectable hose couplings for each of hoses  52  and  53 . Preferably these couplings will have a quick disconnect feature to facilitate the secure connection of the hoses between drive and PTO with rapid disconnection capability. For example, fittings  58  and  57  can be quick-disconnect couplings and thereby allow the flexible hoses to rapidly disengage from the trailer when it is unhitched from the tractor. It is also seen from  FIG. 3  that tractor-mounted PTO  35  is driven by shaft  34  taking power from the tractor engine transmission. Hence, the power supply requirement of a tractor for the novel feed pick up trailer is basically the same as that for a conventional delivery tractor. However, the tractor has no blower drive and no additional auxiliary drive shaft to drive the blower. 
         [0033]      FIG. 2  does not show as separate entities the hydraulic fluid supply and return lines ( 37 ,  38 ,  FIG. 1 ) which carry fluid for operating the trailer unloading conveyors, boom and rotary feed valve. Flow of hydraulic fluid between tractor and trailer now will be described in greater detail with reference to  FIG. 3 . This figure schematically represents the hydraulic liquid flow configuration of the novel feed pick-up system. A hydraulic PTO  70  is shown enclosed in a boundary of dashed lines to indicate that the elements within are located on the tractor. Elements of hydraulic blower  80  are shown in a second dashed line boundary to indicate that they are positioned on the trailer. 
         [0034]    The power takeoff unit is a conventional PTO apparatus. As mentioned, with appropriate hydraulic line and valve modifications, the very same power takeoff unit already present on the residual feed pick-up and delivery tractor to operate the rotary feed valve, discharge conveyors and boom can also be used to operate the feed pick-up blower. Most tractors in a feed supplier&#39;s delivery transportation fleet also have hydraulic power takeoff units because delivery trailers normally have hydraulically powered screw conveyors and booms which they use to unload fresh feed into storage bins at the poultry farms. Hence it is now apparent that most if not every one of the supplier&#39;s fleet of tractors can be readily adapted to power a residual feed pick-up trailer with negligible modification, if any. That is, the standard delivery tractor basically has enough services to operate a pick-up trailer. The need to customize the tractor drive transmission to provide an extra take off shaft to operate the pick-up blower is thus eliminated by this invention. 
         [0035]    Although any standard hydraulic power takeoff unit of adequate hydraulic flow and pressure can be used for this invention,  FIG. 3  illustrates the typical configuration in which unit  70  includes a gear reducer  72  joined by coupling  73  to a tandem hydraulic pump  74 . The gear reducer is motivated in conventional fashion, and commonly is driven by the tractor engine (e.g., via shaft  34 ,  FIG. 2 ) which provides a rotation speed at the coupling effective to operate the pump at pre-selected rate. The power takeoff unit alternatively can have its own power supply such as an electric motor or internal combustion engine. 
         [0036]    By the term “tandem” with respect to the hydraulic pump  74  is meant that the pump has two separate pump heads  76  and  77  simultaneously driven by the gear reducer. While any conventional hydraulic fluid pump can be used, typically, these pumps are preferably gear-type positive displacement pumps which have multiple intermeshing lobes or toothed-gears positioned within a casing. The lobes or gears rotate within the casing to force fixed volumes of hydraulic liquid forward with each revolution. Each pump head generates its own output flow of hydraulic fluid. That is, head  76  generates a hydraulic flow through line  78  and head  77  generates a flow through line  79 . Hydraulic liquid is supplied to both heads via line  71  from liquid reservoir  75 . 
         [0037]    Pressurized hydraulic fluid in lines  78  and  79  flow though hydraulic hoses (collectively depicted as  52 ,  FIG. 2 ) to the trailer where they respectively enter separate parts  86  and  87  of a dual drivehead hydraulic motor  84 . That is, the motor is modular and has two drivehead chambers that convert the power of the supplied hydraulic fluid to mechanical form, usually rotary motion. Both driveheads are joined by coupling  83  to the impeller of blower  82 . It is thus seen that the power from both driveheads combines to motivate the blower. The blower accepts an intake of suction air  46  and discharges pneumatic conveying air  49 . In the illustrated embodiment, all of the spent fluid from drive head  86  returns to reservoir  75  through line  88 . Spent fluid  89  from drivehead  87  moves to regulator  85  which diverts a portion not needed to operate other auxiliary equipment on the trailer to the reservoir through line  81 . Trailer-mounted auxiliary equipment driven by hydraulic fluid, include the rotary feed valve, discharge and conveyors. These are collectively represented schematically in  FIG. 3  only by rotary feed valve unit  90 . Fluid  92  needed to drive the auxiliary equipment passes on to auxiliary hydraulic motors  94  which are coupled to respective auxiliary equipment pieces. Fluid spent from driving the auxiliary functions (collectively, shown as  96 ) is also returned to the reservoir. Preferably to minimize the number of tractor-to-trailer hydraulic hoses, the separate fluid return flows  81 ,  88  and  96  are collected in a common return header  97  which runs into the fluid reservoir. The return header is represented by hose  53  in  FIG. 2 . 
         [0038]    The disclosure herein of tandem pump head power takeoff units and dual drivehead hydraulic motors is optional and non-limiting of the invention. Preference is given to multi-sectioned hydraulic pumps and motors because such equipment is prevalent in some segments of the poultry feed distribution industry. Perhaps such multi-headed hydraulic equipment gained acceptance because they conveniently generated multiple hydraulic flows that could be utilized separately for the variety of different (i.e., rotary feed valve, and conveyor) control functions on the trailers. It should be understood that any style of hydraulic pump and motor of adequate performance characteristics is suitable for use in this invention. 
         [0039]    By way of example, the hydraulic PTO for driving the trailer-mounted hydraulically operated blower of this invention can provide hydraulic fluid output of about 2250 psi and about 25-30 gpm. Typically, the PTO operates at about 1450 rev./min. Representative examples of the type of equipment components that can be adapted for use with this invention are the Parker Hydraulics tandem gear motors PGM620 series (Parker Hannifin Corporation, Youngstown, Ohio) for the dual drivehead hydraulic motor and DuroFlow® Positive Displacement Lobe Blowers/Vacuum Pumps of industrial series 45 (Gardner Denver Blower Division, Peachtree City, Ga.). The DuroFlow Model 4509 is exemplary for being capable of providing at about 3,000 rpm vacuum performance of about 500 cfm with about 27 BHP at 16 in. Hg. vacuum and pressure performance of about 500 cfm with about 52 BHP at 15 psig pressure. 
         [0040]    From the foregoing it should be apparent that a feed supplier can greatly simplify the logistics of operation by having a fleet of substantially uniformly equipped tractors. With respect to feed delivering and picking up, these tractors have the customary hitches for drawing a trailer and a hydraulic PTO unit to supply pressurized hydraulic fluid to the trailer. The supplier also provides as many delivery trailers and one or more pick-up trailers as may be needed in service. The delivery trailers are primarily designed to haul up to large quantities of fresh food from the suppliers stock to the growers&#39; bins. They mainly comprise a tank which may be subdivided with baffles or compartmentalized, a boom and conveyors such as screw-type conveyors for moving the feed from the delivery tank to the destination bin. The pick-up trailer or trailers are equipped substantially as described above and as shown in  FIG. 2 . Any of the supplier&#39;s tractors ordinarily adapted to haul a delivery trailer can thus also operate a pick-up trailer. 
         [0041]    It may be further understood that the use of hydraulics to drive the pick-up trailer-mounted blower eliminates the need to use a mechanical drive for the blower that incorporates a rubber drive belt. Consequently, in the event that the pneumatic conveyor lines on the trailer plug with solids accidentally, there will be no belt to degrade from overheating. Because the blower can continue to run despite such a plug, the suction and discharge lines  49  and  46 , ( FIG. 2 ), respectively, can be fitted with pressure relief valves to admit or discharge air to atmosphere under such circumstances. Then the operator can sense the escape of air through the relief valves, shut down the system and clean out the plugged transfer lines. The need to replace a belt is thus avoided. 
         [0042]    The novel system can be easily retroactively fitted to feed delivery tank trailer in common use very simply as can better be understood with reference to  FIG. 4 . The blower  102  and tandem hydraulic drive motor  103  are mounted on a support  105  and linked by drive shaft  104 . The blower air intake port and air discharge port are labeled  106  and  107 , respectively. It has been found convenient to mount the support under the trailer carriage and preferably near the forward end of the trailer for ease of access for maintenance. Pre-existing hydraulic fluid transfer lines  110 ,  111 ,  112  and  113 , are typically rigid metal pipes mounted on one side of the trailer and run horizontally along the length of trailer. Transfer lines  110 - 112  carry pressurized hydraulic oil  100  from a conventional hydraulic power takeoff unit (PTO), not shown, mounted on the tractor. The pressurized oil is conducted by the transfer lines toward the rear of the trailer to actuate the rotary feed valve  120 , the discharge conveyors  122 , and the discharge boom  124 . Spent oil  126  at slightly lower pressure from each of the service functions is collected in return transfer line  113 . This line moves the oil toward the front of the trailer where it is sent to the reservoir  128  of the PTO on the tractor. 
         [0043]    Prior to modification to install the novel hydraulically driven blower on the trailer, transfer lines  110  and  111  are continuous from the hydraulic hose connection to the tractor at the front of the trailer to the service functions  120  and  122 , respectively. To power the hydraulic drive for the blower on the trailer, these transfer lines are cut and stopped with pipe blanks at points A. Sections of pipe B between the blanks are removed. Appropriate pipe fittings are installed in the transfer lines at points C to carry fluid to and from the blower hydraulic drive. Two new manual three-way valves  114  and  116  are mounted on the trailer frame at a convenient position for operation by the trailer operator. 
         [0044]    The following hydraulic fluid lines are installed between the transfer lines and the hydraulic drive  103 . For a newly fabricated trailer, these lines should be permanent, rigid metal constructions. However, for retroactively fitting an existing trailer, installation can be expedited by making up the hydraulic fluid lines to the drive with good quality, suitably pressure-rated flexible hydraulic fluid transmission hoses. Pressurized hydraulic fluid from line  110  is directed to the common port of three-way valve  114 . One outlet port of this valve supplies first head  103   a  via line  108 . The second output port connects to the continuation of transfer line  110  via line  109 . Each three-way valve  114  and  116  is configured such that fluid can flow from the common port to only one of the outlet ports at any time. Thus fluid can either flow through valve  114  to hydraulic drive head  103   a  or to the rotary valve service  120  via line  110  depending upon which way the valve is set. To drive the blower, the valve should be set to direct the fluid into line  108 . Similarly, oil supply from line  111  is diverted into the common port of valve  116 . One outlet port of this valve connects to second drive head  103   b  via line  118  and the other outlet port connects via line  119  back into transfer line  111  rearward of the removed section B. To operate the blower, the valve is set to direct the hydraulic fluid supply through line  118 . Valves  114  and  116  can be made to be independently operable, however, preference is given to linking the valves such that a single control, such as a lever arm, will operate both valves simultaneously. It would be highly unusual to set one valve cause flow to the blower drive and the other valve to bypass the blower drive. Therefore linking the valves simplifies the task of the operator to direct all hydraulic fluid flow to the blower drive or to bypass the drive with a single action. Hydraulic drive heads  103   a  and  103   b  each respectively have a pressure equalization line  115  and  117  and a flow check valve  125  and  127 . These lines are provided to protect the drive heads from a sudden shock that might occur when valves  114  and  116  are switched to bypass the blower to stop the blower after a feed pick-up operation has loaded excess feed into the trailer tank. When the three-way valves are switched high pressure of fluid in the drive head inlet lines  108  and  118  lower immediately. However, higher pressure fluid is permitted to flow back from the respective drive head discharge lines  123  and  129 . This returning fluid allows the drive heads to continue to turn and to gracefully slow to a stop. At normal operation, the check valves prevent hydraulic fluid from flowing directly to the drive head discharge from the drive head inlet (e.g., to  123  from  108 ). While the blower is operating, all of the spent hydraulic oil discharging from one of the drive heads, e.g.,  129  oil from head  103   b,  flows via line  131  to the return transfer line  113  which transfers the fluid to the power takeoff unit reservoir  128  on the tractor. A portion of the spent hydraulic oil from the other drive head, e.g.,  123  oil from head  103   a,  is used to operate the rotary valve  120  while the blower is in operation. This oil is diverted to transfer line  110  via line  132 . There it passes to the rotary valve drive and is ultimately recovered through the return transfer line  113 . The remainder of the spent oil ( 123 ) from drive head  103   a  is returned to the reservoir through line  131 . A one-way flow check valve  133  in line  132  prevents high pressure hydraulic oil from flowing into the drive head via line  123  when the three-way valve is set to bypass the blower. 
         [0045]    In operation to pick up bulk feed particles, the trailer is connected to any tractor having a hydraulic power takeoff unit suitably sized to drive the blower and is hauled to the pick up site. If not already done, the hydraulic hoses  52 ,  53  ( FIG. 2 ) are connected to the corresponding transfer lines on the trailer and the three-way valves are set to cause fluid to flow into the blower drive heads via lines  108  and  118 . The tractor&#39;s power takeoff unit is energized which activates the blower. Rotary valve  120  also operates due to hydraulic oil flowing through line  133 . The operator can then vacuum sweep up the excess feed particles and load them into the trailer tanks. When loading is completed, the power takeoff unit is shut down and the blower stops operating. The trailer can then be hauled to a new location where the excess feed can be unloaded. To carry out unloading, the operator sets the three-way valves  114  and  116  to the blower bypass positions. When the power takeoff unit on the tractor is started, these valve settings cause the fluid to flow from transfer line  110  through valve  114  into line  109  and further into the continuation of transfer line  110  where it activates the rotary valve  120 . Similarly, hydraulic fluid flows from transfer line  111  through valve  116  to the continuation of transfer line  111  and transfer line  112  via line  119 . This fluid operates the discharge conveyors  122  and boom positioning mechanisms  124  to unload the feed from the tanks. A one-way flow check valve  134  in line  131  (along with check valve  133 ) prevents spent hydraulic oil in return transfer line  113  from flowing into the blower drive heads. Thus the operator can maneuver the boom and operate the discharge conveyors to unload the trailer. 
         [0046]    Although specific forms of the invention have been selected in the preceding disclosure for illustration in specific terms for the purpose of describing these forms of the invention fully and amply for one of average skill in the pertinent art, it should be understood that various substitutions and modifications which bring about substantially equivalent or superior results and/or performance are deemed to be within the scope and spirit of the following claims. In particular, although the disclosure emphasizes the novel system for use in feed distribution services for poultry farming, it is contemplated that the novel technology can also be applied advantageously to the bulk transport of different materials in other industries, for example, the transport and distribution of feed to cattle, sheep, hogs and other livestock, the transport and distribution of seed and granular product of land farming and the bulk transportation of non-agricultural materials such as chemicals.