Hydraulic Actuators Handle Heavy Doors

Hydraulic systems are often the first choice for opening and closing gigantic one-piece doors used on airplane hangars, agricultural buildings, and structures requiring large openings. Sometimes exceeding 100 ft. in width and weighing well over 10,000 lb., these doors need powerful mechanisms to operate smoothly and dependably. Hydraulic power is ideal and adaptable to any size door by increasing cylinder size in proportion to door size and weight.

One-piece doors are preferable in these applications because they swing up and away from the building, and their operation is simple. They do not protrude inside the structure like roll-up doors, which can reduce headroom. Bifold doors, on the other hand, pivot outward as they are raised. This feature presents a different set of advantages and disadvantages. Because bifold doors lift from the bottom, lifting force can be distributed across the width of the door. An electromechanical drive is generally used for these doors, but because one-piece doors must be pivoted from both sides, hydraulics is generally used.

A big advantage of the one-piece doors is that they provide a large, shaded canopy outside the building when open. With hydraulic power, the doors can be clad with almost any material, including heavy glass and steel siding. Entire storefronts have been incorporated into door designs.

Smart Hydraulic Design

Schweiss Doors, Hector, Minn., offers both types and has developed design features specifically addressed to improve hydraulic door operation over other designs. At the heart of the company’s system is a hydraulic gear pump driven by an electric motor ranging in size from 2 to 20 hp. The complete hydraulic power unit (HPU) is a compact package that can be mounted anywhere in a building, whether on the floor or a wall close to the door or farther away.

UL-listed electrical components are housed in control boxes, including contactors, transformers, relays, motor timers, rectifiers, and control fuses. The gear pump is 95% efficient and operates quietly at 1,800 rpm. The HPU also incorporates a 3,000-psi pressure gauge, fluid temperature gauges, and a service filter.

Structural features include a proprietary hinge design that provides considerably greater surface area than standard hinges for distributing the load of the moving door evenly. The patented hinges each feature four connection points, with grease-lubrication and removable hinge pins for extended service life. Spherical bearings connecting cylinders on each side of the door to the door frame and the building accommodate horizontal movement or deflection. They also allow for flexibility of the door and frame without binding on the cylinder pins and brackets.

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How to Decide Between Electric, Pneumatic and Hydraulic Actuators 

Fluid power is a well-established technology; but in case you haven’t noticed, hydraulic actuators have come a long way in the past ten years. But does that mean that fluid power systems are obsolete?

To answer that question, I spoke to experts from automation suppliers Festo and SMAC. Festo carries both electric and pneumatic technology, while SMAC specializes in a variety of types of electric actuators from ball screw-driven devices to linear motors.

According to Jim Ackert, applications specialist at Festo, fluid power systems may not be going anywhere. In many applications where they were once ubiquitous, however, electrics are pushing in.

“For the time being, I think all three technologies have their place in industry,” said Ackert. “But, the flexibility of electric drives, coupled with the fact that the price of electric components has been steadily coming down over the years, makes them more popular and affordable than they once were.”

Tradeoffs Between Electric, Pneumatic and Hydraulic Actuators

It may sound frivolous, but choosing the right actuator technology is a lot like choosing a role-playing game character: the Fighter, Mage and Thief are classic character archetypes in video games, with trade-offs in damage, health and speed. When it comes to actuators, the trade-offs are force, positioning accuracy and speed.

In general, the overlap between the force and speed capabilities of fluid and electric actuators is growing. Electric actuators are even making their way into heavy equipment presses and other traditionally hydraulic-dominated markets.

Read more: How to Decide Between Electric, Pneumatic and Hydraulic Actuators