Hydraulics

For decades, the dump truck industry has been relegated to two sizes of dump pumps; a larger, higher flowing (up to 27GPM) C Series pump, and a smaller, lower flowing (up to 16GPM) G series pump. The smaller size of the G series pump is ideal for trucks with automatic transmissions. New drivers in the truck market are less familiar with manual transmissions, creating a need for more automatics. However, using the G series pump means slower dump cycles for trucks outfitted with automatic transmissions, when compared to their manual counterparts. Slower dump cycles mean less material is being transported and more time is spent onsite, which can diminish profits.

All dump pumps are connected to a power take-off unit (PTO), which is mounted to the truck’s transmission. The PTO draws power from the transmission and allocates it to the dump pump. The truck’s transmission is nestled between the frame rails of the truck chassis. On trucks with manual transmissions, the PTO and dump pump are mounted using an opening on the bottom of the transmission. However, on trucks with automatic transmissions, a PTO mount on the bottom side does not exist.

Automatic transmissions typically have PTO mounts on their side, with limited space between the frame rails for installation. This design creates a space problem. The large C series cannot fit between the side mounting and the frame rails. To fix this problem, a smaller dump pump was designed to fit in the limited space. The G series dump pump produces less flow with a smaller valve, solving the space constraint issue, but resulting in a slower overall dump cycle time.

To close the gap between automatic and manual dump cycles, Parker's Pump & Motor Division has launched a new dump pump that combines the best of both designs into one; a mid-size pump with a larger, integrated dump valve, that can be mounted to automatic transmissions. As a high flowing pump with a smaller footprint, the new pump was deemed the Super G (SG102).

For ideal performance, Parker recommends pairing the Super G with the 280 Series PTO, and SG102 series pump support brackets from Parker Chelsea. Compatible and easy to access equipment means less time is spent on installation of the Super G, meaning that retrofits are quick and easy. Once installed, the Super G provides drivers, using automatic transmissions, faster dump cycles and greater productivity.

The Pump & Motor Division is a market leader in gear pump and low speed-high torque gerotor motors, that continues to blaze a trail in the industry by developing new technologies, while maintaining the high level of service synonymous with Parker. Between its two locations in North Carolina and Tennessee, the division employs decades of industry experience to better serve you and your application.

This article contributed by CT Lefler, marketing product manager and Makenzie NeeSmith, marketing intern, Pump & Motor Division, Parker Hannifin Corporation.

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This is part two of a two-part post explaining how to determine the best size for a hydraulic pump motor and how to scale the size and cost with RMS loading and Hp limiting.

In Part 1 of this post, we discussed the correct way to size an electric motor for a hydraulic pump. Now we’re going to take things a step further by explaining how to safely scale down the size of your motor for increased efficiency and cost-savings.

There are two methods that you can use to safely put a smaller motor to work in your hydraulic pump. One is the Root Mean Square (RMS) method and the other is Hp limiting. Which you choose is based on how the hydraulic pump will be utilized.

Most hydraulic power units do not continuously operate using the same power load, and their flow and pressure levels are constantly changing as various actuators move during the machine cycle.

As an example, during a single cycle, a hydraulic pump might shift from 10Hp for ten seconds to 15Hp for five seconds, 4Hp for thirty seconds, 12Hp for ten seconds, and 5Hp for 20 secs. Although the pump reaches 15 Hp during the cycle, that is not its continuous operating zone. Rather, it is the upper range of the power demand.

In the chart below, you will see that the RMS value in this example is well below 10Hp. This means that as long as the power demand doesn’t exceed 150% of the motor’s rating—and the RMS value doesn’t exceed the motor nameplate rating—an 10Hp motor could be safely used in this application.   

We arrived at the above solution by calculating the varying amounts of power needed throughout the cycle as well as the amount of time that power is used. In short, RMS or root mean squared power represents the integral of the squares of the instantaneous values during a cycle. The mathematical calculation is as follows:

If we take the numbers from the example above and apply them to this equation, the resulting calculation would look like this:

Power (RMS) = SQ.RT. ((10Hp^2x10s + 15Hp^2x5s + 4Hp^2x30s + 12Hp^2x10s + 5Hp^2x20s)/(10s+5s+30s+10s+20s)) = 7.78Hp

NEMA motors can be sized using this technique, IEC motors typically cannot.  If in doubt, contact your motor vendor. When using a VFD make sure the drive can handle occasional overload current. 

Another instance in which a smaller motor may be appropriate is with applications that require high flow at low pressure and high pressure at low flow. In such a case, you can utilize a variable volume pump that is capable of limiting its own power requirements, thus enabling a smaller motor to be used.

Let’s say your system requires a 20 GPM @ 500 PSI during rapid advance and 3000 PSI at 0.5 GPM (clamping). Using the basic (flow x pressure)/(1714 x eff.) formula for sizing that we discussed in Part 1 of this post, you would probably consider selecting a 40Hp electric motor. But wait! Because this application requires high flow at low  pressure and high pressure at low flow, you can use an Hp limiting pump and safely scale down to a 25Hp motor.

Pumps that offer horsepower limiting or other control options can help make your hydraulic system much more efficient while enabling you to conserve energy. Contact your local Parker Hannifin distributor for more information on Hp limiting pumps or for help deciding whether or not choosing a smaller motor is smart choice for your hydraulic pump. And, in case you missed it, check out Part 1 of this post for more detailed information on determining the best motor size for your hydraulic pump.

For more information on Choosing an Efficient Electric Motor for a Hydraulic Pump, contact Parker's Hydraulic Pump and Power Systems Division. 

This article contributed by Tim Beck, manager - system design and application, Parker Hannifin Corporation Hydraulic Pump and Power Systems Division.

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This two-part post explains how to determine the best size for a hydraulic pump motor and how to scale the size and cost with RMS loading and Hp limiting.

Knowing how to right-size an electric motor for your hydraulic pump can help reduce energy consumption and increase operational efficiency. The key is to ensure the pump motor is operating at peak continuous load. But how can you know how much power is needed?

Before you can choose the correct electric motor, you must know how much horsepower (Hp) is required to drive the pump shaft. Generally, this is calculated by multiplying the flow capacity in gallons per minute (GPM) by the pressure in pounds per square inch (PSI). You then divide the resulting number by 1714 times the efficiency of the pump, for a formula that looks like this:

If you’re not sure how efficient your hydraulic pump is, it is advisable to use a common efficiency of about 85% (Multiplying 1714 x 0.85 = 1460 or 1500 if you round up). This work-around simplifies the formula to:

Note: If the pressure is 1500 PSI, you can also estimate 1hp/GPM.

The above formula works in most applications with one notable exception: If the operating pressure of a pump is very low, the overall efficiency will be much lower than 85%. That’s because overall efficiency is equal to mechanical efficiency (internal mechanical friction) plus volumetric efficiency.

Overall efficiency = internal mechanical friction + volumetric efficiency

Internal friction is generally a fixed value, but volumetric efficiency changes depending on the pressure used. Low pressure pumps have high volumetric efficiency because they are less susceptible to internal leakage. However, as the pressure goes up and internal fluids pass over work surfaces such as pistons, port plates, and lubrication points, the volumetric efficiency goes down and the amount of torque required to turn the pump for developing pressure goes up.

Torque (to develop pressure) = Pressure (PSI) x displacement (cu. in.) / 2 PI

This variance makes it very important to know the efficiency of your pump if you’re using it at low pressure! Calculations that do not take low pressure into account will lead to a failed design.  

If you calculate 20 GPM @ 300 PSI with an assumed overall efficiency of 89%, you would probably select a 5 Hp electric motor. However, if you calculate the same 20 GPM @ 300 PSI with the actual overall efficiency of 50%, you would know that you should be using a 7.5 Hp motor. In this example, making an assumption about the efficiency of your pump could result in installing a motor that is too large, driving up your overall operating cost.

There are many contributors to the overall efficiency of a hydraulic pump, and it pays to be as accurate as possible when choosing a motor. A best practice for proper sizing is to use published data from the pump vendor that shows actual input torque vs. pressure or overall efficiency vs pressure. Note that efficiency is also affected by RPM.

Identifying a right-sized motor for your hydraulic pump does not always ensure you are using the most efficient motor. Be sure to read Part 2 of this post to learn how RMS loading and Hp limiting can help you scale down the size of your electric motor to save money while maximizing efficiency.

For more information on Choosing an Efficient Electric Motor for a Hydraulic Pump, contact Parker's Hydraulic Pump and Power Systems Division. 

This article contributed by Tim Beck, retired engineer, Parker Hannifin Corporation Hydraulic Pump and Power Systems Division.

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When it comes to mobile heavy lifting applications, we are increasingly seeing that the electrification market can benefit from integrated, decoupled solutions. These solutions offer an alternative to inefficient coupled power distribution strategies where the internal combustion engine (ICE) is sized for peak energy demand with no energy storage or recovery capabilities. As a result, decoupled power distribution concepts can improve efficiency considerably and allow the employment of smaller, more fuel-efficient ICEs, or even the removal the ICE altogether.

With electrification delivering environmental, sustainability and performance benefits, equipment designers and users are increasingly looking to tap into the enabling technology. If successful, they can also expect to profit from better maintainability, greater safety and compliance with more stringent emissions regulations.

Decoupled solutions

Decoupled solutions add to this list of benefits, not least regarding the potential for a smaller ICE, or eliminating it altogether. In addition, there are advantages relating to energy recovery, power on/off demand and the operation not being dependent on the ICE speed, or torque.

Among the market’s prominent solutions in this area is Parker’s Electro-Hydraulic Pump System (EHPS) for mobile motion system applications. We’ve purposely designed this type of integrated system to provide customers with energy cost savings of up to 50 percent.

The key point here for discerning engineers is that this development has addressed a notable market need for decoupled loads and power distribution. Such a design concept provides enhanced engine management whereby energy storage and recovery functions can be introduced. Furthermore, the size of the drive system can be matched perfectly to requirements, giving power on demand, eliminating any waste and capturing returned energy on load lowering.

Elsewhere, EHPS also proved successful in a hybrid electric reach stacker developed by a key OEM, which again demonstrated fuel savings (30 percent) and productivity improvements with faster responses in lifting, lowering and driving. In addition, maintenance was made easier due to the system’s modular design and self-diagnostic capabilities. In this application, it is predicted that up to 100 tonnes fewer CO2 emissions will be generated based on 5000 hours running time per year.

Conclusion

Ultimately, energy recovery via electrification will of course allow longer equipment usage. Crucially however, this technology will permit customers to satisfy the requirements of the emerging environmental and emissions regulations.

For those worried about risk or ease of adoption, Parker recently unveiled a state-of-the-art electrification system development and validation facility in Warwick, UK. Using the flexibility of high power density, programmable EHP’s (Electro-Hydraulic Pumps), the new facility is able to replicate a large range of loading and duty-cycle profiles, while monitoring system efficiency, energy usage, and concept performance. 

Learn more about Parker's Electro-hydraulic pump system and the benefits it can bring to your project.

Article contributed by James Playdon, Engineering & Marketing Manager, Parker Hannifin

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Machine builders in the European market know that their machines must meet the requirements of the machinery directive if they want to be CE marked and sold. This is not news to anyone. But are you aware that the requirements are written provided that new technical solutions are constantly developed over time?

The Machinery directive, 2006/42/EC, states:

(14) The essential health and safety requirements should be satisfied in order to ensure that machinery is safe; these requirements should be applied with discernment to take account of the state of the art at the time of construction and of technical and economic requirements.

State of the art is a moving target, and it will always be a challenge for machine manufacturers to keep up with the latest developments. Technical solutions evolve and open up new ways of making machines more safe in comparison to the past.

Parker launched IQAN, programmable electronics to help make machinery more safe by enabling smarter safety interlocks in the mid-90s. Examples of its safety functions include load moment limitations on cranes and stopping of all movement when the driver leaves the cab. At that time, the key characteristics of best-in-class systems were robust hardware built for harsh environments and electromagnetic compatibility. These are now considered basic requirements. In the case of IQAN, software specific for developing application software made machines less prone to implementation errors, but there was no established method that machine manufacturers could use to objectively evaluate software. The standards for safety of machinery that existed at this time was very focused on different levels of redundancy, with little consideration of software aspects and analysis of electronics. Standardized solutions could be both cost-prohibitive and fail to address important control system aspects.

With the release of ISO 13849-1:2006 Safety of Machinery, designers received guidance on how to methodically develop a control system with safety functions by focusing on hardware reliability, diagnostics and software quality to reach a desired performance level (PL). The requirements in the standard adapted to the increasing experience of using programmable electronics and the growing availability of component reliability data. The ISO 13849-1 standard allows machine designers to choose the best solution for each part of a safety function. For example, sensors with redundant signals, off-the-shelf controllers certified to IEC 61508 and well-tried reliable hydraulic components.

When Parker introduced the IEC 61508 SIL2 certified controller IQAN-MC3 in 2010, they gave machine manufacturers an effective way to implement SIL2 / PLd safety functions. The IQAN-MC3 controller is designed around the concept that in-depth knowledge of the components is the key to efficient hardware diagnostics. The core diagnostics package includes a technique called challenge-response, a set of cyclic tests that give a good diagnostic coverage without adding too much extra hardware. This gives a realistic hardware cost, but the extensive self-diagnostics firmware does take its toll in calculation speed.

An example of an application where the technology has been deployed is the load moment control of a reach stacker, where stability of a machine is calculated to prevent a machine from overturning. Another example is wheel steering on lift trucks.

As manufacturers of mobile machinery gain experience from using standards for the most critical safety functions, the next step is to bring this structured approach to normal operating functions. In mobile, it has always been difficult to distinguish some of the normal operating functions from the safety functions. Load moment limitations and stopping of all movement when the driver leave the cab are examples of functions whose primary purpose is to achieve safety. Stopping the implement hydraulics when the operator lets go of the lever is part of normal machine operation, but it can also be a safety function. As mobile machinery controllers with safety certification become more affordable, it makes sense to step up the requirements on all motion controlling functions.

The new series of IQAN-MC4xFS is a perfect example of how state of the art is changing.

IQAN-MC4xFS builds on the experience of the IQAN-MC3, reusing the proven IQAN software platform that is the foundation for all IQAN masters. It has also inherited the concept for power driver outputs with a combined high-side and low-side switching and detection of wiring faults for safety related loads. The core electronics has also evolved. A key component is the Infineon microcontroller designed for both automotive and machinery applications. This is designed from the start with hardware supported self-diagnostics. Compared to its predecessor the IQAN-MC3, this makes the IQAN-MC4xFS more run-time efficient; it can execute larger applications at a shorter cycle time.

With one of the larger modules IQAN-MC42FS or IQAN-MC43FS, the machine designer has a choice to use one certified controller of on all sections on a hydraulic directional control valve. This gives a cost-effective way to meet safety function Performance Level c without adding extra hydraulic components. For functions requiring the higher Performance Level d, IQAN-MC4xFS can be used to read spool position sensors and actuate pump unloading valves to have a second hydraulic shutdown path.

The MC4xFS gives the possibility to meet current and future requirements of functional safety without compromising the performance of the machine functionality. It makes it possible to create both safe and user-friendly functionality in a cost-efficient way. The technology development on electronics has taken us to a state of the art level that makes it possible to implement safety functions in and on virtually all motion control functions in a machine. It lets you focus on what matters most - machine functionality. Learn more.

Article contributed by Gustav Widén, systems engineer electronics, Parker Hannifin Manufacturing Sweden AB.

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Hybrid Actuation System (HAS) are making localized control viable for both mobile and industrial applications. This new technology give the benefits of power and resiliency found in hydraulics while garnering the benefits of energy efficiency and plug and play simplicity found in electromechanical solutions.

HAS are high force self-contained linear actuation systems that bring electrification to where the work needs to be performed. They are integrated with field-proven components into localized configurations that look and feel like an electrical actuator yet have the power density and fail-safe characteristics associated with traditional hydraulics. HAS solutions consolidate the entire hydraulic system into a single component integral to the actuator that hooks up to a local control point with plug-and-play simplicity. Each unit presents a compact footprint and represents only a modest addition to overhead.

By localizing the power source, HAS eliminate not only the centralized power unit with its electric motor, pump reservoir, and related valving, but also all the hoses and tubes connecting them to the actuator. This dramatically reduces system complexity, simplifies troubleshooting and saves energy by deploying it incrementally as needed, without all the horsepower losses commonly found in valve operated hydraulic designs.

From harsh mobile applications to industrial automation, this innovative technology provides opportunities for downsizing and streamlining hydraulic control systems while increasing the flexibility and efficiency of processes and operations.

Parker’s HAS 500 is a new hybrid design combines the controllability of traditional electromechanical actuators with the power density, longer life and fail safe conditions commonly found on traditional hydraulic systems. The result is an improved actuation solution for 1-2 axis of motion control. Bore sizes ranging from 2" through 8" bore with no limit on stroke, mount or rod modifications.

Learn more about the benefits of HAS and how they can improve your operational performance by downloading our Hybrid Actuator Simplifies Electrification of Hydraulic Cylinders white paper.

This post was contributed by Bruce Besch, alternative motion sales manager, Parker Hannifin's Cylinder Division.

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