Hydraulics

Choosing between electronic or manual control for hydrostatic pumps

More hydrostatic pumps are being fitted with electronic controls. While this does provide higher upfront costs in the short term, the long-term benefits are greater.
By Zek Grantham February 9, 2019
Courtesy: CFE Media

Times are changing in the mobile hydraulics world with the integration of electronics into hydraulic systems. Many have felt the effects of Tier 4 and all the additional electronics, wiring harnesses, and displays that have been forced upon them with these regulations.

The result has been a hesitance to build machines with larger diesel engines in order to stay under the Tier 4 requirements. At the same time, manufacturers feel like they are being forced into using electronics on machines that always have been manually operated. However, hydrostatic pumps can benefit from the addition of electronics. An electronically controlled hydrostat can provide a cleaner set up that is less labor-intensive to install, has fewer leak points, and is more responsive overall.

Manually-controlled hydrostatic pump pros and cons

A manually-controlled hydrostatic pump is very user-friendly. The users know what they’re going to get from the pump in direct correlation to the input. Operators feel in complete control because they are stroking the swashplate on the pump by manually engaging it through a lever on the pump.

The idea that users cannot have the same amount of control or “feathering” with an electronically controlled hydrostat is wrong. An electronic proportionally controlled hydrostat can provide more control because users can remove any lag or play often found in manually controlled systems. This responsiveness also can be tailored to correlate with engine speed so users are able to be more responsive on low RPMs for fine feathering and then less responsive for a smoother control at higher RPMs.

With the addition of the electronic controls on the hydrostat, the pump’s costs will increase. Users also have to add a controller and electronic joystick/foot pedal for sending the command signal along with a wiring harness. The sticker shock of these components, compared to a standard manually controlled pump, can scare off most customers. However, users need to understand this isn’t an apple-to-apple comparison.

To better understand the comparison, users need to do a full cost analysis of the manually controlled system, including hoses, fittings, and installation labor costs. To offset or justify the rest of the additional cost, users must look at what other features they gain by adding electronics into the system.

Electronically-controlled hydrostat features and benefits

A common concern with electronics is troubleshooting the system when something goes down. A small display that communicates directly with the controller and can call out any errors the system is showing can be added to the system. This display also can be connected to the engine, which gives users the ability to read engine fault codes.
If a display is incorporated into the system design, many of the gauge’s warning lights and signals could be eliminated. This gives users a cleaner set up and often removes some cost from the system. At the very least, the final cost should even out.

Another benefit is eliminating user fatigue. Manually stroking and destroking a pump puts a lot of strain on the operator. However, this is not an issue with an electronically controlled pump. The spring force in the joystick/foot pedal governs the resistance a user feels to control the pump’s swashplate. Unlike a manually operated system, this force does not change when the pressure on the system increases or decreases.

Incorporating electronics into hydraulic systems is the way of the future. However, it doesn’t have to be viewed as an overwhelming task to get started or a negative change to a machine. The benefits that come with the electronically controlled system can quickly outweigh any additional upfront costs.

Zek Grantham is an account manager at Cross Co., a CFE Media content partner. This article originally appeared on Cross Co.’s mobile hydraulics and controls’ blog. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, cvavra@cfemedia.com.

MORE ANSWERS

Keywords: pumps, electronic control, manual control

Manually controlled hydrostatic pumps are user friendly and popular with operators.

Electronically controlled hydrostatic pumps can provide even greater control than a manually-controlled pump.

Electronically controlled pumps have greater upfront costs, but it also reduces user fatigue.

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What applications could benefit from an electronically controlled hydrostatic pump?

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Zek Grantham
Author Bio: Account manager for Cross Company's mobile hydraulics and control systems group