Patent Publication Number: US-11649838-B2

Title: Temperature regulation system for vehicle hydraulic system

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/810,989, filed Mar. 6, 2020, which claims the benefit of U.S. Provisional Patent Application No. 62/841,657, filed May 1, 2019, both of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     Vehicles and machinery often include hydraulically driven components. During cold weather operating conditions, operation of the hydraulically driven components may be negatively impacted. 
     SUMMARY 
     One embodiment relates to a hydraulic system for a machine. The hydraulic system includes a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump coupled to the reservoir, a driver positioned to drive the pump to pump the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid from the pump to operate a controllable machine component. The driver is independent of a prime mover of the machine. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to monitor the temperature of the hydraulic fluid and selectively activate at least one of the heater or the pump to thermally regulate the hydraulic fluid to maintain the hydraulic fluid within a target temperature range. 
     Another embodiment relates to a hydraulic system for a machine. The hydraulic system includes a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump positioned to drive the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid from the pump to selectively operate a controllable machine component. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to activate the pump to drive the hydraulic fluid through the hydraulic circuit with the heater deactivated to facilitate cooling the hydraulic fluid in response to the temperature of the hydraulic fluid exceeding or approaching a maximum temperature threshold. 
     Still another embodiment relates to a hydraulic system. The hydraulic system includes a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump positioned to drive the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid to selectively operate a controllable component. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to (i) activate at least one of the heater or the pump to facilitate heating the hydraulic fluid in response to the temperature of the hydraulic fluid falling below or approaching a minimum temperature threshold and (ii) activate the pump to drive the hydraulic fluid through the hydraulic circuit with the heater deactivated to facilitate cooling the hydraulic fluid in response to the temperature of the hydraulic fluid exceeding or approaching a maximum temperature threshold. 
     This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a refuse vehicle, according to an exemplary embodiment. 
         FIG.  2    is a perspective view of a mixer vehicle, according to an exemplary embodiment. 
         FIG.  3    is a perspective view of a firefighting vehicle, according to an exemplary embodiment. 
         FIG.  4    is a perspective view of an airport firefighting vehicle, according to an exemplary embodiment. 
         FIG.  5    is a perspective view of a lift vehicle, according to an exemplary embodiment. 
         FIG.  6    is a perspective view of a lift vehicle, according to another exemplary embodiment. 
         FIGS.  7 A- 7 K  are various schematic diagrams of a hydraulic circuit of a vehicle, according to an exemplary embodiment. 
         FIG.  8    is a schematic diagram of a control system of a vehicle, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting. 
     According to an exemplary embodiment, a vehicle or machine includes a hydraulic circuit having a heater and one or more hydraulic actuators configured to facilitate manipulating controllable vehicle/machine components (e.g., a boom, lift arms, a mixer drum, a pumping system, outriggers, etc.). In cold weather conditions, hydraulic fluid can become overly viscous and negatively impact performance of the controllable vehicle/machine components. By way of example, the engine of the vehicle or machine may stall (e.g., from increased load to drive a pump that pumps the hydraulic fluid, etc.) and/or lead to slow cycle times when the temperature of hydraulic fluid drops below of a target operating range. Further, traditional systems may include manually activated heater circuits that are often forgotten to be activated by operators and require constant operator monitoring. According to an exemplary embodiment, the heater of the present disclosure is configured to facilitate automatically heating and maintaining the temperature of hydraulic fluid within the hydraulic circuit at or above a target temperature, absent any operator input. The heater of the present disclosure therefore enables improved performance by providing consistent performance throughout an operating day and eliminating any need for operator input. 
     According to the exemplary embodiment shown in  FIGS.  1 - 8   , a vehicle or machine, shown as vehicle  10 , includes (i) a control system, shown as control system  150 , and (ii) a hydraulic circuit, shown hydraulic circuit  200 . According to an exemplary embodiment, the control system  150  is configured to control operation of components of the hydraulic circuit  200  to maintain a temperature of hydraulic fluid therein within a target operating range absent any user interaction. 
     As shown in  FIGS.  1 - 4   , the vehicle  10  includes a chassis, shown as frame  12 ; a front cabin, shown as cab  20 , coupled to the frame  12  (e.g., at a front end thereof, etc.) and defining an interior, shown as interior  22 ; and a rear assembly, shown as rear assembly  30 , coupled to the frame  12  (e.g., at a rear end thereof, etc.). The cab  20  may include various components to facilitate operation of the vehicle  10  by an operator (e.g., a seat, a steering wheel, hydraulic controls, a user interface, switches, buttons, dials, etc.). As shown in  FIGS.  1 - 6   , the vehicle  10  includes a prime mover, shown as engine  14 , coupled to the frame  12 . As shown in  FIGS.  1 - 3   , the engine  14  is positioned beneath the cab  20 . As shown in  FIG.  4   , the engine  14  is positioned within the rear assembly  30  at the rear of the vehicle  10 . As shown in  FIGS.  1 - 6   , the vehicle  10  includes a plurality of tractive elements, shown as wheel and tire assemblies  16 . In other embodiments, the tractive elements include track elements. According to an exemplary embodiment, the engine  14  is configured to provide power to the wheel and tire assemblies  16  and/or to other systems of the vehicle  10  (e.g., a pneumatic system, a hydraulic system, etc.). The engine  14  may be configured to utilize one or more of a variety of fuels (e.g., gasoline, diesel, bio-diesel, ethanol, natural gas, etc.), according to various exemplary embodiments. According to an alternative embodiment, the engine  14  additionally or alternatively includes one or more electric motors coupled to the frame  12  (e.g., a hybrid vehicle, an electric vehicle, etc.). The electric motors may consume electrical power from an on-board storage device (e.g., batteries, ultra-capacitors, etc.), from an on-board generator (e.g., an internal combustion engine genset, etc.), and/or from an external power source (e.g., overhead power lines, etc.) and provide power to the systems of the vehicle  10 . 
     According to the exemplary embodiments shown in  FIG.  1   , the vehicle  10  is configured as a front loading refuse vehicle (e.g., a garbage truck, a waste collection truck, a sanitation truck, a recycling truck, etc.). In other embodiments, the vehicle  10  is configured as a side-loading refuse truck or a rear-loading refuse truck. As shown in  FIG.  1   , the rear assembly  30  is configured as a rear body, shown as refuse compartment  40 . According to an exemplary embodiment, the refuse compartment  40  facilitates transporting refuse from various waste receptacles within a municipality to a storage and/or processing facility (e.g., a landfill, an incineration facility, a recycling facility, etc.). By way of example, loose refuse may be placed into the refuse compartment  40  where it may thereafter be compacted. The refuse compartment  40  may provide temporary storage for refuse during transport to a waste disposal site and/or a recycling facility. In some embodiments, the refuse compartment  40  includes a hopper volume and a storage volume. Refuse may be initially loaded into the hopper volume and thereafter compacted into the storage volume. According to an exemplary embodiment, the hopper volume is positioned between the storage volume and the cab  20  (i.e., refuse is loaded into a position of the refuse compartment  40  behind the cab  20  and stored in a position further toward the rear of the refuse compartment  40 ). In other embodiments, the storage volume is positioned between the hopper volume and the cab  20  (e.g., in a rear-loading refuse vehicle, etc.). As shown in  FIG.  1   , the refuse compartment  40  includes a pivotable rear portion, shown as tailgate  42 . The tailgate  42  is pivotally coupled to the refuse compartment  40  and movable between a closed orientation and an open orientation by actuators, shown as tailgate actuators  43  (e.g., to facilitate emptying the storage volume, etc.). 
     As shown in  FIG.  1   , the vehicle  10  includes a lift mechanism/system (e.g., a front-loading lift assembly, etc.), shown as lift assembly  44 , having a pair of lift arms, shown as lift arms  45 , coupled to the frame  12  and/or the rear assembly  30  on each side of the vehicle  10  such that the lift arms  45  extend forward of the cab  20  (e.g., a front-loading refuse vehicle, etc.). In other embodiments, the lift assembly  44  extends rearward of the rear assembly  30  (e.g., a rear-loading refuse vehicle, etc.). In still other embodiments, the lift assembly  44  extends from a side of the rear assembly  30  and/or the cab  20  (e.g., a side-loading refuse vehicle, etc.). The lift arms  45  may be rotatably coupled to frame  12  with a pivot (e.g., a lug, a shaft, etc.). As shown in  FIG.  1   , the lift assembly  44  includes actuators, shown as lift arm actuators  46  and articulation actuators  48  (e.g., hydraulic cylinders, etc.), coupled to the frame  12  and/or the lift arms  45 . The lift arm actuators  46  are positioned such that extension and retraction thereof rotates the lift arms  45  about an axis extending through the pivot, according to an exemplary embodiment. The lift arms  45  may be rotated by the lift arm actuators  46  to lift a refuse container over the cab  20 . The articulation actuators  48  are positioned to articulate the distal ends of the lift arms  45  coupled to the refuse container to assist in tipping refuse out of the refuse container into the hopper volume of the refuse compartment  40  (e.g., through an opening in the refuse compartment  40 , etc.). The lift arm actuators  46  may thereafter rotate the lift arms  45  to return the empty refuse container to the ground. 
     According to the exemplary embodiment shown in  FIG.  2   , the vehicle  10  is configured as a concrete mixer truck. As shown in  FIG.  2   , the rear assembly  30  of the vehicle  10  includes a concrete drum assembly, shown as drum assembly  50 . According to an exemplary embodiment, the vehicle  10  is configured as a rear-discharge concrete mixing truck. In other embodiments, the vehicle  10  is configured as a front-discharge concrete mixing truck. 
     As shown in  FIG.  2   , the drum assembly  50  of the vehicle  10  includes a drum, shown as mixing drum  52 . The mixing drum  52  is coupled to the frame  12  and disposed behind the cab  20  (e.g., at a rear and/or middle of the frame  12 , etc.). As shown in  FIG.  2   , the drum assembly  50  includes a drive system, shown as drum drive system  54 , that is coupled to the frame  12 . According to an exemplary embodiment, the drum drive system  54  is configured to selectively rotate the mixing drum  52  about a central, longitudinal axis thereof. In one embodiment, the drum drive system  54  is driven by the engine  14 . In other embodiments, the drum drive system  54  is individually powered, separate from the engine  14  (e.g., with a motor, an independently driven actuator, etc.). According to an exemplary embodiment, the axis is elevated from the frame  12  at an angle in the range of five degrees to twenty degrees. In other embodiments, the axis is elevated by less than five degrees (e.g., four degrees, three degrees, etc.) or greater than twenty degrees (e.g., twenty-five degrees, thirty degrees, etc.). In an alternative embodiment, the vehicle  10  includes an actuator positioned to facilitate selectively adjusting the axis to a desired or target angle (e.g., manually in response to an operator input/command, automatically according to a control scheme, etc.). 
     As shown in  FIG.  2   , the mixing drum  52  of the drum assembly  50  includes an inlet, shown as hopper  56 , and an outlet, shown as chute  58 . According to an exemplary embodiment, the mixing drum  52  is configured to receive a mixture, such as a concrete mixture (e.g., cementitious material, aggregate, sand, etc.), with the hopper  56 . The mixing drum  52  may additionally include an injection port. The injection port may provide access into the interior of the mixing drum  52  to inject water and/or chemicals (e.g., air entrainers, water reducers, set retarders, set accelerators, superplasticizers, corrosion inhibitors, coloring, calcium chloride, minerals, and/or other concrete additives, etc.). According to an exemplary embodiment, the injection port includes an injection valve that facilitates injecting the water and/or the chemicals from a fluid reservoir (e.g., a water tank, etc.) into the mixing drum  52  to interact with the mixture, while preventing the mixture within the mixing drum  52  from exiting the mixing drum  52  through the injection port. The mixing drum  52  may include a mixing element (e.g., fins, etc.) positioned within the interior thereof. The mixing element may be configured to (i) agitate the contents of mixture within the mixing drum  52  when the mixing drum  52  is rotated by the drum drive system  54  in a first direction (e.g., counterclockwise, clockwise, etc.) and (ii) drive the mixture within the mixing drum  52  out through the chute  58  when the mixing drum  52  is rotated by the drum drive system  54  in an opposing second direction (e.g., clockwise, counterclockwise, etc.). The chute  58  may include an actuator positioned such that the chute  58  is selectively pivotable to reposition the chute  58  (e.g., vertically, laterally, etc.) and therefore an angle at which the mixture is expelled from the mixing drum  52 . 
     According to the exemplary embodiment shown in  FIG.  3   , the vehicle  10  is configured as a single rear axle quint fire truck. In other embodiments, the vehicle  10  is configured as a tandem rear axle quint fire truck. In still other embodiments, the vehicle  10  is configured as another type of fire apparatus such as a tiller fire truck, an aerial platform fire truck, a mid-mount fire truck, etc. As shown in  FIG.  3   , the rear assembly  30  includes stabilizers, shown as outriggers  60 , coupled to the frame  12  and an aerial assembly, shown as ladder assembly  70 , disposed on top of the rear assembly  30 . The outriggers  60  may be selectively extended from each lateral side and/or rear of the rear assembly  30  to provide increased stability while the vehicle  10  is stationary and the ladder assembly  70  is in use (e.g., extended from the vehicle  10 , etc.). The outriggers  60  may be supplemented by or replaced by one or more downriggers coupled to the front and/or the rear of the frame  12 . The rear assembly  30  further includes various compartments, cabinets, etc. that may be selectively opened and/or accessed for storage and/or component inspection, maintenance, and/or replacement. 
     As shown in  FIG.  3   , the ladder assembly  70  includes a plurality of ladder sections, shown as ladder sections  72 , that are slidably coupled together such that the ladder sections  72  are extendable and retractable. The ladder assembly  70  further includes a base platform, shown as turntable  74 , positioned at the base or proximal end of the ladder sections  72 . The turntable  74  is configured to rotate about a vertical axis such that the ladder sections  72  may be selectively pivoted about the vertical axis (e.g., up to 360 degrees, etc.). As shown in  FIG.  3   , the ladder assembly  70  includes an implement, shown as water turret  76 , coupled to the distal end of the ladder sections  72 . The water turret  76  is configured to facilitate expelling water and/or a fire suppressing agent (e.g., foam, etc.) from a water storage tank and/or agent tank onboard the vehicle  10  and/or from an external water source (e.g., a fire hydrant, a separate water truck, etc.). In other embodiments, the ladder assembly  70  does not include the water turret  76 . In such embodiments, the ladder assembly  70  may include an aerial platform coupled to the distal end of the ladder sections  72 . 
     According to the exemplary embodiment shown in  FIG.  4   , the vehicle  10  is configured as an airport rescue firefighting (“ARFF”) truck. In other embodiments, the vehicle  10  is still another type of fire apparatus. As shown in  FIG.  4   , the rear assembly  30  include compartments, shows as compartments  80 . The compartments  80  may be selectively opened to access components of the vehicle  10 . As shown in  FIG.  4   , the rear assembly  30  includes a pump system (e.g., an ultra-high-pressure pump system, etc.), shown as pump system  90 , disposed within the compartments  80  of the rear assembly  30 . The pump system  90  may include a high pressure pump and/or a low pressure pump coupled to a water tank  92  and/or an agent tank  94 . The pump system  90  is configured to pump water and/or a fire suppressing agent from the water tank  92  and the agent tank  94 , respectively, to an implement, shown as water turret  96 , coupled to the front end of the cab  20 . 
     According to the exemplary embodiment shown in  FIG.  5   , the vehicle  10  is configured as a lift device or machine (e.g., a boom lift, etc.). In other embodiments, the vehicle  10  is another type of vehicle (e.g., a skid-loader, a telehandler, a scissor lift, a fork lift, a boom truck, a plow truck, a military vehicle, etc.). As shown in  FIG.  5   , the frame  12  supports a rotatable structure, shown as turntable  100 , and a first lift system or boom assembly, shown as boom  110 . According to an exemplary embodiment, the turntable  100  is rotatable relative to the frame  12 . According to an exemplary embodiment, the turntable  100  has a counterweight positioned at a rear of the turntable  100 . In other embodiments, the counterweight is otherwise positioned and/or at least a portion of the weight thereof is otherwise distributed throughout the vehicle  10  (e.g., on the frame  12 , on a portion of the boom  110 , etc.). 
     As shown in  FIG.  5   , the boom  110  includes a first boom section, shown as lower boom  112 , and a second boom section, shown as upper boom  114 . In other embodiments, the boom  110  includes a different number and/or arrangement of boom sections (e.g., one, three, etc.). According to an exemplary embodiment, the boom  110  is an articulating boom assembly. In one embodiment, the upper boom  114  is shorter in length than lower boom  112 . In other embodiments, the upper boom  114  is longer in length than the lower boom  112 . In some embodiments, the boom  110  is a telescopic, articulating boom assembly. By way of example, the upper boom  114  and/or the lower boom  112  may include a plurality of telescoping boom sections that are configured to extend and retract along a longitudinal centerline thereof to selectively increase and decrease a length of the boom  110 . 
     As shown in  FIG.  5   , the lower boom  112  has a lower end pivotally coupled (e.g., pinned, etc.) to the turntable  100  at a joint or lower boom pivot point. The boom  110  includes a first actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as lower lift cylinder  120 . The lower lift cylinder  120  has a first end coupled to the turntable  100  and an opposing second end coupled to the lower boom  112 . According to an exemplary embodiment, the lower lift cylinder  120  is positioned to raise and lower the lower boom  112  relative to the turntable  100  about the lower boom pivot point. 
     As shown in  FIG.  5   , the upper boom  114  has a lower end pivotally coupled (e.g., pinned, etc.) to an upper end of the lower boom  112  at a joint or upper boom pivot point. The boom  110  includes an implement, shown as platform assembly  116 , coupled to an upper end of the upper boom  114  with an extension arm, shown as jib arm  118 . In some embodiments, the jib arm  118  is configured to facilitate pivoting the platform assembly  116  about a lateral axis (e.g., pivot the platform assembly  116  up and down, etc.). In some embodiments, the jib arm  118  is configured to facilitate pivoting the platform assembly  116  about a vertical axis (e.g., pivot the platform assembly  116  left and right, etc.). In some embodiments, the jib arm  118  is configured to facilitate extending and retracting the platform assembly  116  relative to the upper boom  114 . As shown in  FIG.  5   , the boom  110  includes a second actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as upper lift cylinder  122 . According to an exemplary embodiment, the upper lift cylinder  122  is positioned to actuate (e.g., lift, rotate, elevate, etc.) the upper boom  114  and the platform assembly  116  relative to the lower boom  112  about the upper boom pivot point. 
     According to an exemplary embodiment, the platform assembly  116  is a structure that is particularly configured to support one or more workers. In some embodiments, the platform assembly  116  includes an accessory or tool configured for use by a worker. Such tools may include pneumatic tools (e.g., impact wrench, airbrush, nail gun, ratchet, etc.), plasma cutters, welders, spotlights, etc. In some embodiments, the platform assembly  116  includes a control panel to control operation of the vehicle  10  (e.g., the turntable  100 , the boom  110 , etc.) from the platform assembly  116  and/or remotely therefrom. In some embodiments, the control panel is additionally or alternatively coupled (e.g., detachably coupled, etc.) to the frame  12  and/or the turntable  100 . In other embodiments, the platform assembly  116  includes or is replaced with an accessory and/or tool (e.g., forklift forks, etc.). 
     According to the exemplary embodiment shown in  FIG.  6   , the vehicle  10  is configured as a lift device or machine (e.g., a scissor lift, etc.). As shown in  FIG.  6   , the vehicle  10  includes a second lift system (e.g., a scissor assembly, etc.), shown as lift assembly  130 , that couples the frame  12  to a platform, shown as platform  132 . The frame  12  supports the lift assembly  130  and the platform  132 , both of which are disposed directly above the frame  12 . In use, the lift assembly  130  extends and retracts to raise and lower the platform  132  relative to the frame  12  between a lowered position and a raised position. 
     As shown in  FIG.  6   , the vehicle  10  includes one or more actuators, shown as leveling actuators  148 , coupled to each corner of the frame  12  and having feet or ground pads coupled to a free end thereof. According to an exemplary embodiment, the leveling actuators  148  extend and retract vertically between a stored position and a deployed position. In the stored position, the leveling actuators  148  are raised and do not contact the ground. In the deployed position, the leveling actuators  148  contact the ground, lifting the frame  12 . The length of each of the leveling actuators  148  in their respective deployed positions may be varied to adjust the pitch (i.e., rotational position about a lateral axis) and the roll (i.e., rotational position about a longitudinal axis) of the frame  12 . Accordingly, the lengths of the leveling actuators  148  in their respective deployed positions may be adjusted such that the frame  12  is leveled with respect to the direction of gravity, even on uneven or sloped terrains. The leveling actuators  148  may additionally lift the wheel and tire assemblies  16  off the ground, preventing inadvertent driving of the vehicle  10 . In other embodiments, the vehicle  10  does not include the leveling actuators  148 . 
     As shown in  FIG.  6   , the lift assembly  130  includes a number of subassemblies, shown as scissor layers  140 . Each of the scissor layers  140  includes a first member, shown as inner member  142 , and a second member, shown as outer member  144 . In each scissor layer  140 , the outer member  144  receives the inner member  142 . The inner member  142  is pivotally coupled to the outer member  144  near the centers of both the inner member  142  and the outer member  144 . Accordingly, the inner members  142  pivot relative to the outer members  144  about a lateral axis. The scissor layers  140  are stacked atop one another to form the lift assembly  130 . Each inner member  142  and each outer member  144  has a top end and a bottom end. The bottom end of each inner member  142  is pivotally coupled to the top end of the outer member  144  immediately below it, and the bottom end of each outer member  144  is pivotally coupled to the top end of the inner member  142  immediately below it. Accordingly, each of the scissor layers  140  is coupled to one another such that movement of one scissor layer  140  causes a similar movement in all of the other scissor layers  140 . The bottom ends of the inner member  142  and the outer member  144  belonging to the lowermost of the scissor layers  140  are coupled to the frame  12 . The top ends of the inner member  142  and the outer member  144  belonging to the uppermost of the scissor layers  140  are coupled to the platform  132 . Scissor layers  140  may be added to or removed from the lift assembly  130  to increase or decrease, respectively, the maximum height that the platform  132  is configured to reach. 
     As shown in  FIG.  6   , the lift assembly  130  includes one or more actuators (e.g., hydraulic cylinders, pneumatic cylinders, motor-driven leadscrews, etc.), shown as lift actuators  146 , that are configured to extend and retract the lift assembly  130 . The lift actuators  146  are pivotally coupled to an inner member  142  at one end and pivotally coupled to another inner member  142  at the opposite end. These inner members  142  belong to a first scissor layer  140  and a second scissor layer  140  that are separated by a third scissor layer  140 . In other embodiments, the lift assembly  130  includes more or fewer lift actuators  146  and/or the lift actuators  146  are otherwise arranged. The lift actuators  146  are configured to actuate the lift assembly  130  to selectively reposition the platform  132  between the lowered position where the platform  132  is proximate the frame  12  and the raised position where the platform  132  is at an elevated height. In some embodiments, extension of the lift actuators  146  moves the platform  132  vertically upward (extending the lift assembly  130 ), and retraction of the linear actuators moves the platform  132  vertically downward (retracting the lift assembly  130 ). In other embodiments, extension of the lift actuators  146  retracts the lift assembly  130 , and retraction of the lift actuators  146  extends the lift assembly  130 . In some embodiments, the outer members  144  are approximately parallel and/or contact one another when the lift assembly  130  is in a stored position. The vehicle  10  may include various components to drive the lift actuators  146  (e.g., pumps, valves, compressors, motors, batteries, voltage regulators, etc.). 
     As shown in  FIG.  8   , the hydraulic circuit  200  is coupled to (i) one or more sensors, shown as sensors  250 , and (ii) one or more components of the vehicle  10 , shown as controllable vehicle components  260  (e.g., the lift assembly  44 , the tailgate  42 , the outriggers  60 , the downrigger(s), the ladder assembly  70 , the pump system  90 , the mixing drum  52 , the chute  58 , the boom  110 , the lift assembly  130 , the ground pads, etc.). As shown in  FIGS.  7 A- 8   , the hydraulic circuit  200  includes a reservoir, shown as fluid reservoir  210 , a fluid driver, shown as pump  220 , one or more actuators, shown as actuators  230 , a temperature regulation system (e.g., a heater system, a heater, a heating element, heating assembly, etc.), shown as heater circuit  240 , and an auxiliary circuit, shown as auxiliary flow circuit  270 . According to an exemplary embodiment, the fluid reservoir  210  is configured to store hydraulic fluid, the pump  220  is configured to drive or pump the hydraulic fluid from the fluid reservoir  210  and throughout the hydraulic circuit  200  (e.g., to the heater circuit  240 , to the actuators  230 , etc.), and the actuators  230  are configured to receive the hydraulic fluid from the pump  220  to operate the controllable vehicle components  260 . As shown in  FIGS.  7 B and  7 C , the pump  220  is driven by the engine  14  and/or driven by an independent source, shown as driver  300  (e.g., an electric motor, an independent engine, etc.). The actuators  230  may include hydraulic actuators (e.g., the tailgate actuators  43 , the lift arm actuators  46 , the articulation actuators  48 , actuators such as a hydraulic motor or hydraulic pump of the drum drive system  54 , actuators of the chute  58 , actuators of the outriggers  60 , actuators of downriggers, actuators of the ladder assembly  70 , actuators such as a hydraulic pump of the pump system  90 , the lower lift cylinder  120 , the upper lift cylinder  122 , the lift actuators  146 , the leveling actuators  148 , etc.) driven by hydraulic fluid. The sensors  250  may include one or more temperature sensors positioned to acquire temperature data indicative of a temperature of the hydraulic fluid at one or more locations within the hydraulic circuit  200  (e.g., within the fluid reservoir  210 , the heater circuit  240 , the pump  220 , and/or the actuators  230 ; upstream of the heater circuit  240 , the pump  220 , and/or the actuators  230 ; downstream of the heater circuit  240  and/or the pump  220 ; etc.). 
     According to an exemplary embodiment, the heater circuit  240  is positioned to heat the hydraulic fluid upstream of the actuators  230  such that the hydraulic fluid is provided to the actuators  230  above a minimum temperature threshold and within a target temperature range. As shown in  FIG.  7 D , the heater circuit  240  is configured to facilitate thermally regulating the hydraulic fluid within the fluid reservoir  210 . As shown in  FIGS.  7 E and  7 F , the heater circuit  240  is configured to facilitate thermally regulating the hydraulic fluid upstream of the pump  220 . As shown in  FIGS.  7 G and  7 H , the heater circuit  240  is configured to facilitate thermally regulating the hydraulic fluid downstream of the pump  220 . According to an exemplary embodiment, the heater circuit  240  is configured to facilitate thermally regulating the hydraulic fluid without having to engage the actuators  230  to operate the controllable vehicle components  260  (e.g., allowing the hydraulic fluid to be thermally regulated while not being used such that the hydraulic fluid is always above the minimum temperature threshold of the target temperature range when needed to drive the actuators  230 , etc.). As shown in  FIGS.  71  and  7 J , the heater circuit  240  includes a conduit, shown as conduit  242 , and one or more valves, shown as valves  244 , that selectively permit the hydraulic fluid to flow therethrough to engage with a heater, shown as heater  246 , when the temperature of the hydraulic fluid needs to be heated (and may bypass the heater circuit  240  when heating thereof is not needed). For example, a controller may control the one or more valves  244  such that the hydraulic fluid may (i) flow through the heater circuit  240  when the one or more valves  244  are in a first position, orientation, or configuration (e.g., open, etc.) and (ii) bypass the heater circuit  240  when the one or more valves  244  are in a second position, orientation, or configuration (e.g., closed, etc.). In some embodiments, such as in  FIGS.  7 E and  7 G , the hydraulic fluid always flows through the heater circuit  240 , but the heater circuit  240  is only active and heating the hydraulic fluid when necessary. In other embodiments, such as in  FIGS.  7 D,  7 F, and  7 H , the heater circuit  240  does not receive the hydraulic fluid, but rather the heater circuit  240  is a heating element positioned within the fluid reservoir  210  and/or along the flow of the hydraulic fluid (i.e., the hydraulic fluid flows around the heater circuit  240  to be heated rather than flowing through the heater circuit  240 ). Accordingly, the heater circuit  240  may be or include a heater or heating element, a fluid conduit, and/or one or more valves. 
     According to the exemplary embodiment shown in  FIG.  8   , the control system  150  for the vehicle  10  includes a controller, shown as controller  160 . In one embodiment, the controller  160  is configured to selectively engage, selectively disengage, control, and/or otherwise communicate with components of the vehicle  10 . As shown in  FIG.  8   , the controller  160  is coupled to the hydraulic circuit  200  (e.g., the pump  220 , the actuators  230 , the heater circuit  240 , etc.) and the sensors  250 . In other embodiments, the controller  160  is coupled to more or fewer components. 
     The controller  160  may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital-signal-processor (DSP), circuits containing one or more processing components, circuitry for supporting a microprocessor, a group of processing components, or other suitable electronic processing components. According to the exemplary embodiment shown in  FIG.  8   , the controller  160  includes a processing circuit  162  having a processor  164  and a memory  166 . The processing circuit  162  may include an ASIC, one or more FPGAs, a DSP, circuits containing one or more processing components, circuitry for supporting a microprocessor, a group of processing components, or other suitable electronic processing components. In some embodiments, the processor  164  is configured to execute computer code stored in the memory  166  to facilitate the activities described herein. The memory  166  may be any volatile or non-volatile computer-readable storage medium capable of storing data or computer code relating to the activities described herein. According to an exemplary embodiment, the memory  166  includes computer code modules (e.g., executable code, object code, source code, script code, machine code, etc.) configured for execution by the processor  164 . 
     According to an exemplary embodiment, the controller  160  is configured to (i) receive and monitor the temperature data acquired by the sensors  250  and (ii) selectively activate the heater circuit  240  (e.g., the heater, the one or more valves, etc.) and/or operate the pump  220  to drive the hydraulic fluid into the heater circuit  240  (e.g., in embodiments where the heater circuit  240  is external from the fluid reservoir  210 , etc.) in response to the temperature of the hydraulic fluid within the hydraulic circuit  200  approaching or falling below a minimum threshold temperature of the target temperature range for the hydraulic fluid to heat the hydraulic fluid with the heater circuit  240 . Such activation of the heater circuit  240  is independent of any operator input and may be independent of operation of the controllable vehicle components  260  (e.g., the actuators  230  do not need to be operated to heat the hydraulic fluid with the heater circuit  240 , the hydraulic fluid can be heated regardless of the controllable vehicle components  260  being active, etc.). 
     In some embodiments, the controller  160  is configured to monitor the temperature data acquired by the sensors  250  and operate that pump  220  to drive the hydraulic fluid through the hydraulic circuit  200  (e.g., with the heater deactivated, etc.) or an independent circuit (e.g., like the heater circuit  240  but without the heater, the heater circuit  240  with the heater thereof deactivated, the auxiliary flow circuit  270 , etc.) coupled to the hydraulic circuit  200  in response to the temperature of the hydraulic fluid within the hydraulic circuit  200  approaching or exceeding a maximum threshold temperature of the target temperature range for the hydraulic fluid to cool the hydraulic fluid. By way of example, as shown in  FIG.  7 K , the auxiliary flow circuit  270  includes a conduit, shown as auxiliary flow conduit  272 , and one or more valves, shown as valves  274 , that facilitate selectively permitting a flow of hydraulic fluid through the auxiliary flow conduit  272  (e.g., when activated by the controller  160 , by diverting the hydraulic fluid from the hydraulic circuit  200  into the auxiliary flow conduit  272  of the auxiliary flow circuit  270 , etc.). Running the hydraulic fluid through the piping of hydraulic circuit  200  or the independent circuit may permit cooling the hydraulic fluid without the need for a hydraulic cooling system. 
     As utilized herein, the terms “approximately,” “about,” “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims. 
     It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples). 
     The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic. 
     References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure. 
     The hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry that is specific to a given function. The memory (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, the memory is communicably connected to the processor via a processing circuit and includes computer code for executing (e.g., by the processing circuit or the processor) the one or more processes described herein. 
     The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. 
     Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps. 
     It is important to note that the construction and arrangement of the vehicle  10 , the control system  150 , and the hydraulic circuit  200  as shown in the various exemplary embodiments is illustrative only. Additionally, any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein. Although only one example of an element from one embodiment that can be incorporated or utilized in another embodiment has been described above, it should be appreciated that other elements of the various embodiments may be incorporated or utilized with any of the other embodiments disclosed herein.