Mechatronic Actuators

For engineers looking for a simple, turnkey solution to mechatronics challenges, prepackaged actuators may be just the ticket.

A good example of what is now available for applications ranging from lawn and garden to medical to office furniture is the actuator line produced by LINAK, a Danish company with North American offices in Louisville.

Well known for actuators used in hospital beds and other medical settings, LINAK has introduced a new actuator, the LA36, designed to withstand harsh outdoor applications such as lawn equipment and motorized road signs. During development, engineers tested the actuator for performance under mechanical and electrical strain, as well as in extreme cold and heat. It also was tested for resistance to chemicals, salt spray and high-pressure cleaning.

Besides durability, the LA36, as LINAK application engineer Doug Heilman explains it, offers engineers real plug-and-play benefits and a host of mechatronics features. These include:

• A 12, 24 or 36-V dc permanent magnet motor that links to the power supply of the device it supports, such as lawn equipment

• Maximum thrust ranging from 1700N to 6800N, depending on the gear ratio and spindle

• Maximum speed of 68 mm/sec, depending on load and spindle

• Mechanical overload protection through integrated slip clutch

• Built-in brake with self-locking ability

• Optional built-in end stop switches, Hall Effect sensor and potentiometer for accurate positioning

Heilman adds that LINAK can tailor the actuator to meet specific customer needs, such as range of stroke, cabling or mounting devices. Among the key design criteria discussed with the customer: specifications on required speed and force.

Indiana-based Dixie Chopper recently chose the LA36 actuator to raise and lower the mowing deck on its Coatesville Classic and Silver Eagle lines of heavy-duty lawn mowers. Mounted between the cutting deck and the main frame of the lawnmower, the actuator replaces a previous manual-lift device. Dixie chose the electronic unit over a competing hydraulic design.

“Advantages of using electric systems include quiet and smooth motion control, durability, energy efficiency, higher accuracy and cleaner, more environmentally safe use,” says Mike Pecore, LINAK technical services coordinator. “Hydraulics’ systems also operate under extreme pressure, which can cause hoses to wear over time and explode into messy oil leaks.”

Pecore points out that hydraulic actuators are larger and heavier than an electro-mechanical system, because of the need for an oil tank, pump, filter system and bulky hoses. Hydraulics also adds to assembly and mounting costs, says Pecore.

Brad Church, R&D manager at Dixie Chopper, notes the addition of the LA36 to its mowers has meant easier, smoother height adjustment. “This makes it possible for people who could not use a manual pedal to raise and lower the deck with ease,” says Church. “LINAK actuators have also held up extremely well in the field.”

To make it easier to integrate its actuators, LINAK typically sends its 3D Pro/ENGINEER CAD files to customer companies, notes Pecore. These customers in turn may use simulation software to model the actuator’s motion. LINAK also provides prototype units for customer field test.