A new hydraulic pump for construction work

Stick with what works or start with a clean sheet of paper? Both approaches to product design have their merits, and the new ZU4 hydraulic pump has succeeded in combining the proven and the innovative

Stick with what works or start with a clean sheet of paper? Both approaches to product design have their merits, and in the new ZU4 hydraulic pump Enerpac engineers succeeded in combining the proven and the innovative.

The challenge was to develop a next-generation two-stage portable electric hydraulic pump to serve the construction industry in tasks such as foundation repair, post-tensioning, and powering medium to large cylinders and hydraulic tools.

The goals were increased ease of use, improved operating characteristics, longer life, and easier maintenance.

For jobsite equipment, true portability ranks high on the list of desirable features.

The new pump is compact, light in weight, and sports a thermally insulated handle.

An optional tubular steel skid frame adds an extra-wide stance and two-person carrying ability to smaller models, while larger units include extra-large side handles.

Enerpac ZU4 series electric pump used for cable tensioning with pull cylinder.

For motor-driven equipment, real portability involves more than size and weight.

The design team combined the high power-to-weight ratio of a universal motor with hydraulic circuit and drive-end improvements to maximize hydraulic output and minimize current draw.

In fact, the ZU4 draws 18% less current than comparable pumps.

The universal motor offers two other important jobsite benefits.

One is a low starting current draw much reducing the likelihood of tripping breakers at start-up.

The other is outstanding tolerance for low supply voltage.

A bulkier, heavier induction motor tolerates under voltage poorly, quickly overheating.

The universal motor is a match for jobsite conditions, able to operate satisfactorily from a long extension cord or a portable generator.

Working under a hot sun can be brutal for a hydraulic power source.

The ZU4 has a high-efficiency, cooler-running design, combined with a heavy-duty FRP composite shroud: these help it to resist the ravages of sun as well as rain.

An optional heat exchanger stabilises oil temperature at 54 degree Celsius or less for a 21 degree Celsius ambient, permitting operation under direct sun without overheating.

In addition to providing a cool grip, the composite handle enhances safety because it is an electrical insulator.

The control pendant also combines weather resistance and safety, incorporating sealed switches and operating on only 15VDC.

The foregoing are only a few of the ZU4 innovations.

An outstanding feature is the optional back-lit LCD display.

The display provides information such as pump usage (hour and cycle counts), pressure readout (with optional pressure transducer), and self-test/diagnostic modes, all in a choice of six languages.

When it comes to controlling the output, ZU4 pumps can be specified with manual or solenoid valves in seven configurations.

All feature several gauge ports and user adjustable relief valves that allow the operator to set the working pressure for each job.

The ZU4 design team achieved extended pump life through attention to items such as.

* Reduced number of moving parts increases reliability.

* Reduced internal temperature rise means longer life, especially for polymeric components and tools.

* Heavy-duty, oversize bearings increase pump life.

* Submerged, oil bath lubrication improves pump life.

* Rotating components are balanced during production to reduce vibration.

* The high-strength FRP composite shroud provides environmental and damage protection.

* A new motor brush design increases brush life by a factor of four.

When the ZU4 motor brushes eventually wear down, an "auto-stop" feature stops the motor to prevent expensive commutator damage.

If an "auto-stop" occurs, the easily accessible brushes can be rapidly replaced in the field.

A feature seldom found in this type of product is the replaceable check valves used in the radial-piston high pressure pump.

Designers can strive for high quality, ease of use, endurance, and maintainability, but the proof of the pudding is in testing, and the more of it, the better.

The ZU4 pump is no "90-day wonder"! A multi-year programme of design, development, bench testing, and field testing in a variety of applications resulted in a product that lives up to its promise of ease of use in a tough, reliable package.

Key ZU4 specifications are: 700 bar maximum operating pressure; oil flow 1,0 l/min at 700 bar: 4, 8, 10, 20 and 40 litres.

Models are offered for either 115V or 230V operation.

The ZU4 was developed by Enerpac, a unit of the US-based Actuant group of companies.

Enerpac has a long history in manufacturing all types of high pressure hydraulic equipment and systems for industry and construction, dating back to the early 1900s when the company manufactured water pumps for the legendary Ford Model T, followed by hydraulic jacks.

Today, Enerpac leads the global market in high pressure hydraulics.

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