Variable Flow Open Center Delivers Constant Efficiency

Following new, more stringent Tier IV diesel engine emissions regulations, Rayco, an environmental equipment designer for the tree care and landscape industries, took the opportunity to develop a more efficient, powerful and compact stump cutter, the RG165T-R. In comparison to previous designs that utilized diesel engines, Rayco’s new stump cutter is centered around a powerful 165 HP gasoline engine.

As a result of the new gasoline design, the equipment’s envelope size was reduced and components were eliminated, such as, after treatment systems, diesel exhaust fluid and electronics. In addition to the robust gasoline engine, the RG 165T-R also packs a closed-circuit hydrostatic cutter wheel drive system that delivers full engine HP to the cutter wheel, completing every job in its path.

Stump cutting presents unique operating scenarios with each cycle. A pump and motor must be able to power through different obstacles at each job site. From technical support to high-quality hydraulic components to quick, on-time delivery, Parker enabled Rayco to develop its new industry-leading stump cutter. 

The initial RG165T-R prototype was created using the Parker Series F12 182cc bent axis motor, along with a competitor’s 90cc closed circuit pump. However, during initial rounds of testing, the competitor’s 90cc closed circuit pump struggled with performance and reliability issues, along with the potential for long lead times. 

When Rayco reached out to Parker applications team recommended an alternative - the compact, high-performance C Series 81cc hydrostat piston pump and promptly delivered a unit for testing. During subsequent testing of the Parker pump and motor combination, the team worked with Rayco engineers to dial in the performance.

By incorporating these two Parker components, Rayco engineers were able to exceed multiple performance targets. These targets included a 20 percent decrease in heat generation while increasing system efficiency by 10 percent over alternative test units. The C Series pump delivered excellent power density and paired perfectly with the 182cc F12 motor. The combination also translated into the optimal cutter wheel speed, which increased torque output to the cutter teeth by 10%. Another and unexpected benefit of the system was a tighter radius of the wood chips to the machine, resulting in less operational risk during the stump grinding process. 

 

 

 

Parker’s Hydraulic Pump and Power Systems Division has been designing pumps and transmission for over 50 years. The division is the result of the Parker piston pump business's acquisition of Denison Hydraulics and the merger with the Parker Oildyne Division. These two businesses combined have extended Parker's product offering to include the quality compact hydraulic products and systems the division has been pioneering since 1955. To learn more about the products, visit www.parker.com/hps or contact the team. 

 

Article contributed by Justin Wheeler, product manager, and Wes Jackson, application engineer for Parker Hannifin's Hydraulic Pump an Power Systems Division.

 

 

 

 

 

 

 

 

 

 

Related articles:

New Hydraulic System on Sugarcane Harvester Exceeds Performance Goals

Engine Power Management in Construction Equipment

Essential Criteria for Selecting the Right Motor for your Hydraulic Application

 

Traditionally, agricultural sprayer machines were custom-built on a four-wheel chassis. These custom-built units were heavy, expensive and not easily adapted to other farm applications. Sprayers are typically used to apply herbicides, insecticides and fertilizer. Naturally, it would be more practical if a machine that could be used for other functions – such as tilling, loading, and baling.

One manufacturer designed a retrofit using unconventional technologies which resulted in a three-wheel flotation spraying applicator. The new vehicle is less heavy, costs 20 to 50 percent less and is more versatile because it's designed to accomplish more than one function. The sprayer exerts lower ground pressure and more affordable than traditional machinery.

The three-wheeled commercial applicator was designed by retrofitting a mid-range (50 to 120 hp), two-wheel-drive tractor chassis with three major innovations:  

• Hydraulic wheel steering
• A suspension fork
• Flotation tires  
   

A break from convention 

Tractors of this size generally have hydraulically assisted steering using a hydraulic cylinder and mechanical linkage assembly. In place of the typical front-wheel steering cylinder,  the manufacturer used a Helac helical hydraulic rotary actuator. Parker's Helac L30-65E-FT-180-S1-O-H rotary actuator produces a steering angle of up to 180 degrees and contains a bearing to support the load.  

The rotary actuator is a part of the steering super structure, providing the strength and flexibility the vehicle requires without unnecessary weight, complexity and maintenance required of mechanical linages. It supports a thrust load of 8000 pounds and accommodates 423,000 pounds per inch of bending moment capacity. It transmits 55,000 pounds per inch of steering torque when fully loaded. The L30 series actuator’s design makes it capable of angular displacement of 360-degrees or more.  

The tractor’s original-equipment hydraulic power unit supplies pressurized fluid for steering and other hydraulic functions. Maximum system pressure is 2950 psig with eight gallons per minute of flow but the steering function generally operates at pressure of 1500 to 2000 psig. The only modification needed to the tractor’s original hydraulic system is a higher displacement steering unit. This is because a rotary actuator requires more fluid to move the wheel through its entire range of motion than a cylinder does. The plumbing of the steering control unit is routed directed to the actuator, eliminating sections of hose and fittings otherwise required by the cylinder.  

Height and orientation of the sprayer boom are also controlled with hydraulics. A five-spool solenoid valve routes hydraulic fluid to and from cylinders that raise, lower, rotate, and pivot the prayer boom. Furthermore, an open-center motor, controlled by an electronic flow-control valve, supplies the driving torque to apply the fertilizer or other substance to crops. The retrofit package also includes a suspension style swing arm fork with twin air springs capable of supporting loads to 8000 pounds above the front tire. The air springs’ pressure is adjustable for different loads for smooth riding in the roughest of field conditions. The manufacturer supplied an electric air compressor to generate the pneumatic power for raising pressure in the air springs. The fork’s open front allows for easy access for changing or repairing the front tire. The fork is 50 inches wide, allowing use of huge, 44.00-inch tires for the maximum flotation and the potential for ground pressure as low as four psig.  

 

An integrated solution 

The cutaway above shows initial position of piston and output shaft. Pressurized fluid entering the inlet port pushes on the piston; a stationary ring hear causes the piston to rotate clockwise. At right, teeth on the output shaft mesh with those on the ID of the piston, causing the shaft to rotate clockwise relative to the piston. Pressuring the B port returns the piston and shaft to their initial positions.

 

The actuator used for steering and load support is Parker’s Helac L30-65 actuator. This actuator not only provides a simpler, less expensive structure than alternative designs but also can generate the high torque needed to steer such a large wheel assembly under full load. Previously the manufacturer used steering cylinders, bearings and multiple joints before designing in the sliding spline actuator. With cylinders, all the external moving parts were exposed to the elements. The stress on the joins was high because each steering cylinder had a clevis pin at each end. Stress concentrated on each pin created high wear points, which increased maintenance. Worn pins also allowed side loads to be transmitted to the piston rod. This accelerated wear on the rod and piston bearings increased the occurrence of seal leakage.  

A helical rotary actuator is ideal for this type of high torque application 
 

The actuator used in the manufactuer's sprayer retrofit is composed of three basic parts: a housing, a central through shaft and an annular piston. Helical gear teeth on the shaft mesh with matching teeth on the inner circumference of the piston; a second set of helical teeth of opposite hand on the outer circumference of the piston engage the housing’s integral ring gear. The double helix gear design works to compound shaft rotation. The rotation of the shaft is almost twice that of the piston. The result is a slender, compact, symmetrical design that generates high torque, is highly tolerant of shock loads, and has none of the house protrusions found in alternative designs.

Characteristics of the helical rotary actuator make it ideal for applications requiring high torque within a small envelope, attributable, primarily, to its sliding-spline operation. Because all spline teeth remain engaged at all times, loads are equally distributed over the teeth. This results in high tolerance to the stock loads. Backlash is minimal – approximately 1°. Furthermore, the integral bearing design enables the actuator to support heavy radial, moment and thrust loads without the need for additional, external bearings. The integral bearing design also produces a clean, compact assembly for a wide variety of applications, including construction and mining equipment, refuse cart dumpers – anywhere compact size, high torque, and wide angle of rotation are needed. Aside from the inherent compact size of the actuator, the integral bearings and large drilled-and-tapped mounting holes make it easy to design the actuator info a structure and simplifies installation.   
 

Benefits provide an edge 
 

The manufacturer significantly benefited from switching to Parker’s Helac rotary actuators in three distinct ways:

• The load bearing and steering capability was integrated into one package: Parker’s Helac actuator allowed the manufacturer to replace multiple external components and operate as a complete steering and bearing system in a single rugged component.  
• Low maintenance and zero leakage: Bearings, seals and torque-generating splines are completely sealed and lubricated by the hydraulic fluid inside the actuator housing, resulting in low maintenance and zero leakage. 
• Compact design and simple installation: Bolts are used to mount the feet of the actuator directly to the modified tractor frame.  The tractor’s steering yoke attaches directly to the top and bottom threaded bolt circles of the actuator’s load-bearing shaft.  

Parker’s Helac actuators offer a compact package that provides all the support for the load as well as the hydraulic turning needs without adding unnecessary weight. Seal leakage is eliminated and there are fewer maintenance issues since all moving parts are safely enclosed in a cylindrical envelope. Visit www.parker.com/cylinder for more information about Parker’s various actuators. 

 

Planning on attending IFPE 2020?

Five Ways Quickfit Oil Change System Can Increase Your Equipment ROI - IFPE 2020 logo - Parker HannifinTo learn more about Parker’s off-road machinery solutions stop by Booth #S80245 at IFPE/CONEXPO-Con/AGG in Las Vegas March 10 – 14.

 

Article contributed by Dan Morgado, applications engineer, Parker Hannifin's Cylinder Division.

 

 

 

 

 

Related blogs:

Lifters Designed with Rotary Actuators Dump Waste More Effectively

Unique Tilting Coupler Technology Gives Construction Firm Competitive Edge

 

Parker Chelsea’s Power Take-Off (PTO) is designed and built to meet the demands of the mobile equipment industry. The Chelsea PTO is intended to provide a long service life, both on-highway and off-highway. In order to maximize the life of Chelsea’s PTOs, it is important to have the PTO in proper use and constantly maintain the PTO as well. 

The Chelsea PTO application worksheet and owner’s manual will help you properly specify your PTO and install it. However, the understanding of how a power shift PTO operates will help the troubleshooting process run more smoothly and effectively. For power shift operation, when a power shift PTO is engaged, a solenoid is energized. Air or hydraulic fluid then compresses a clutch pack in the PTO. This locks the PTO output gear to the output shaft and allows work to be done. When the power shift PTO is disengaged, the solenoid de-energizes. Air or hydraulic fluid deadheads against the valve. From there, air is released to atmosphere through a valve, and hydraulic fluid exhausts into the PTO. 

Here are some breakdowns of the potential causes and solutions for troubleshooting the PTO. It is first important to understand that many problems from a Power Shift PTO are the result of incorrect plumbing. A good first procedural step can be found in the Owner’s Manual, which is to compare what pressure is coming from the air or hydraulic source against what pressure is entering the PTO. 

PTO unit not engaging

Dealing with the PTO unit not engaging, these are some of the potential causes with solutions for shifting problems from Power Shift PTOs. (Probable causes are listed in a logical test sequence. Don’t assume any one thing is wrong.)

  PTO unit engaging but not operating under system load

There are situations where the PTO will engage but may not operate under system load. Here are some potential causes and solutions for Power Shift PTOs.

PTO engages without switching the solenoid valve

An issue run into can be the relation between Power Shift PTOs and the solenoid valve. Here are some potential causes and solutions for Power Shift PTOs engaging without switching on the solenoid valve. 

  PTO not disengaging

Potential shifting problems with Power Shift PTOs may lead to the PTO not disengaging. Here are some potential causes and solutions for Power Shift PTOs. 

  Electronic overspeed control operation

Chelsea has developed the next generation of Overspeed Controls for Power Shift PTOs. This system helps prevent the driver from going down the road with the PTO engaged and prevents the power take-off and driven equipment from being operated at excessive speeds. When the Electronic Overspeed Control Operation (EOC control) is changed to the “on” position, it energizes a solenoid valve that pressurizes the clutch pack. This then engages the PTO. A main feature of the EOC is the measuring of speed of the PTO electronically and uses that measurement in comparison to the selected overspeed RPM setting. If/when the PTO exceeds the preselected RPM setting, the EOC will de-energize the solenoid valve, disengaging the PTO. The PTO will remain disengaged until the speed has been reduced to the preselected reset speed. At that time, the PTO will re-engage. 
It is a very simple set up with easy set-up buttons. LED lighting is outputted in three settings for great visibility in the EOC. When the PTO is in overspeed protection mode, audio and visual blinking overspeed warning alerts the operator. This system can be used in applications including LP Gas Trucks, Water Trucks, Fire and Rescue, Aerial Devices, Dump Truck & Trailers, Snow and Ice Removal. Learn more on our Electronic Overspeed Control product page.

This article was contributed by Michael Mabrouk, marketing leadership associate, Chelsea Products Division, Parker Hannifin Corporation.  

 

 

 

 

Related articles:

Ten Frequently Asked Questions You Should Know About PTOs

Understanding Why There are So Many Options for Mounting a PTO

What’s All the Noise About with My Power Take-Off (PTO)?