Niche Builder
 click to enlarge> Image 2:Custom Equipment's Hybrid is built for high-rise applications. |
August 18, 2004 - Self-propelled vertical lifts lack the platform capacity needed by many trades working in high-rise construction, while "elevator class" scissor lifts often have too many bells and whistles to be pragmatic. With that in mind, Custom Equipment, West Bend, Wis., introduces a micro-size scissor lift to meet the unique needs of this niche market.
Time capsule
In the 1980s, Economy Engineering ventured into the market of miniature self-propelled vertical lifts for use inside high-rise buildings with a product called the Pole Cat. This machine had limited success because the market had not yet embraced the need for a piece of equipment compact enough to fit into an elevator. Because working heights were often less than 12 feet, ladders and scaffolding ruled. Many trades still did not realize the value of being self-propelled even at low ceiling heights.
In the years that followed, other attempts to penetrate this market included a one-person self-propelled lift from Get Smart Scaffold Co. and UpRight's TM12. All these products shared a common design-a cantilevered platform elevated by a mast or telescoping tube assembly. The drawback to this approach was a limited platform size-big enough for a person and a few tools but certainly not large enough to carry dry wall, conduit, or HVAC materials.
Then came compact "elevator class" scissor lifts offering 15- and 19-foot platform heights. Typically these units were small enough to fit inside elevators and light enough to operate on upper floors. Their inherently longer, larger decks with deck extensions made them more practical. Most important to their acceptance was that they became readily available in rental fleets-a key to the development of any new market. The elevator class has grown so much that today dozens of compact scissors lifts can be found on any high-rise job, whether it be new construction or remodeling.
Introducing the micro class
Custom Equipment, West Bend , Wis. , has developed a product tailored to the high-rise application-a micro-sized scissors lift delivering features the market expects in a full-size scissor lift while reducing the platform loading height, total weight, and the overall machine size. Additionally, the company's goal is to keep operation and maintenance as simple as possible.
Custom Equipment was established in 1981 by Steve Kissinger, a former engineer at Mayville Engineering Company. Custom Equipment initially designed and built hydraulic scissors worktables and prototypes for other aerial work platform manufacturers. In 1987 the company began developing a low-profile scissors mechanism for use in the mausoleum industry and has since become a leading supplier of casket lifts-shipping units all over the world. After several years of field testing and refinements, Custom Equipment is now applying the low-profile scissor design to a self-propelled personnel lift.
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The HybridT micro scissor lift features a 30-inch wide chassis but delivers a spacious deck measuring 25"x66" plus a 30" deck extension. The chassis is narrow enough to pass through a standard door opening. The 750-pound capacity platform rises to 10 feet and lowers to just 23 inches off the floor in the collapsed position. For full specifications, see Image 3.
The Hybrid derives its name from the fact that the electric and hydraulic systems function independently from each other. Isolating these systems is the key to the company's simplistic design philosophy.
Separation of power
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The hydraulics are limited exclusively to the lift function. Additionally, the pump motor, check valve, lift/lower and emergency lowering control are integrated into a single unit. This 1-hp package is supplied by Monarch Hydraulics Inc., Grand Rapids , Mich. The self-sufficient package should make for exceptionally easy troubleshooting and servicing.
Likewise, the drive and steering systems are all electric. A simple microprocessor and motor controller, supplied by Curtis Controls of Mt. Kisco, N.Y., feed precisely metered power to a pair of electric drive wheel motors. These motors, which operate independently, are located inside a single housing. The drive system features an integral spring-applied and electrically released parking brake that is sandwiched between the two motors. An easy-to-access lever protruding from the rear of the machine releases the brake for free wheeling. Also included in the brake-motor package are drive reducers located between the motors and the wheels. The reducers provide approximately 18:1 final drive ratio.
Although unique to a lift equipment application, the steering system incorporates a tried-and-true screw actuator built by Duff Norton, Charlotte , N.C. , similar to those used on machine tools. The tie rod is linked to a bell crank that throws each set of front steering wheels into a tight Ackerman-geometry steering angle. The result is 15-inch inside turning radius. Coupled with the 63.5-inch overall length, the Hybrid will have little trouble negotiating even the most cluttered job sites. To minimize wheel scrubbing, Custom Equipment utilizes a dual wheel set rather than the more common static wheel set-up. (See Image 7.) The steering wheel set is centered on the spindle so they counter-rotate when turning. This is an important consideration for operating on carpet and some designer floor surfaces.
Operational impressions
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To take advantage of the large-for-its-size deck, the Hybrid can handle up to 750 pounds-more than enough for two workers, tools, and materials. A working height of 16 feet accommodates the ceilings in most high-rise applications. The aluminum diamond plated deck sits low with the first step into the platform only 20 inches off the ground. Platform access is further simplified with the use of a swinging entrance gate. The gate incorporates a solid middle and top rail that affords a 25-inch wide entrance. A bungee-style spring causes the gate to automatically close. Downward leverage supports the 30-inch deck extension, which rides on the platform's guardrail system. Because the supports ride directly on the powder coated guardrails, I fear this could lead to premature paint deterioration.
A tidy control box includes a beefy joystick, produced by Happ Electronics, Elk Grove Village , Ill. , for drive. A flawless proportional drive system is quiet and smooth at any speed or platform height, which is typical of a motor-control driven unit. Just as important, deceleration is void of jerking or abrupt stops. For example, in a simulated panic stop from a top speed of 3 mph, the Hybrid decelerated smoothly to a standstill in less than half its 63.5-inch length. In my experience, this is an appropriate distance in most emergency situations.
I operated the unit on the truck loading dock at about a 20° incline. The unit delivered plenty of power to climb and brake on the incline. The microprocessor allows the ramping speed to be customized by a service technician. I found that the steering was very smooth and since this system is independent from the drive there was no variation or surge when activated while traveling. The steering actuator could, however, be improved with a slightly faster operational speed to facilitate quicker maneuvering.
No-brainer service
The entire electrical system is simple and easy to figure out. The microprocessor is equipped with a flash code to indicate any problems with the drive motors, wiring, or controls. And a single common ground point for all electrical connections is a real plus for tracing electrical problems.
Power for the 24-volt system is supplied by a pair of deep cycle 12-volt batteries wired in series. On the surface, this battery pack might seem small, but keep in mind that the Hybrid is designed to be super efficient. Direct drive and electric steering combined with a very low 1,150-pound GVW help make it so. I was told that internally performed cycle tests indicate that the unit is more than capable of working two to three shifts between charges.
The low gross vehicle weight leads me to highlight another benefit of the Hybrid-it's light floor loading. Many applications require a limited PSI to protect flooring, but this unit's overall low PSF allow it to work in some areas previously inaccessible by a self-propelled lift with these capabilities. A great example of this would be the elevated floors found in computer rooms. Unloaded, the Hybrid only applies 48 PSI wheel load and 87 PSF machine floor load.
Structurally this little jewel is rock-solid. All scissors and steering pivot points are connected with 1-1/2" pins, which admittedly, is overkill in a few places. The pins ride on maintenance-free DU bushings. The scissors stack is a proven design that Custom Equipment has been producing for years on other products.
hen it comes to paint finish, no corners have been cut. All surfaces are powder coated with a finish tested to a minimum of 500 hours salt spray. Other important features include forklift pockets, integrated pothole protection, non -marking tires, and tilt alarm. List price for the Hybrid is $12,500. For more information, call 866-334-0756.
The Hybrid's innovative design is ideally suited for its intended purpose in high-rise applications. As for maintenance-simple is a relative term-but in the context of scissor lifts, maintaining this machine should be a walk in the park.
Likes
- Control system delivered flawlessly smooth operation.
- Isolating the hydraulic and electric systems is a key to the simple design.
- The unit features high-quality construction.
- A very low loading height makes platform entry easy.
Dislikes
- The slide-out deck is supported by the guardrails-paint finish will be put to the test.
- The steering operation was a tad slow
