6 DOF FAQs
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Hydraulic or Electric?
Which type to select usually depends on the application. We manufacture electric 6-DOF platforms up to 3,000 lb payloads and hydraulic payloads up to 30,000 lbs.
Hydraulic systems are usually smoother running and will run continuously for in excess of 20 years.
The use of oil has been a concern in the past, however, the use of mineral based oils has effectively eliminated this problem.
Electric systems (depending on the design) have many more moving parts and can have a life in excess of 10 years.
Power requirements for electric systems is greater than hydraulic systems since the entire capacity of each motor must be available at all times, resulting in greater demand and consumption.
The choice, really depends on your application and conditions.
Power Requirements
Two power sources are required for hydraulic systems:
- 120vac/1ph/20amp for the controls system
- 230-460/3/60/XXX amps [220-380/3/50/XXX amps] for the HPU
Note: Rule of thumb when considering the efficiency of typical motors is 1HP approx = 1KW for estimating purposes.
Example: One 6-DOF motion platform requires a 25 horsepower motor and it would draw 67 Amps @230/3/60.
HPU Acoustical Levels
The Hydraulic Pumping Unit (HPU) will generate nominally a 90 dBA sound level.
It should be located away from the platform or housed in an acoustical enclosure to limit sound levels to the low 70 dBA values.
Typically an acoustical enclosure using four inches of acoustical batting will provide excellent reduction.
HPU Ventillation
The enclosure or room where the HPU is located needs to be properly vented or air-conditioned.
The HPU heat exchanger is typically sized to reject 1/3 of the HPU motor horsepower in heat.
For order-of-magnitude sizing, when considering efficiencies of a typical heat exchange process; use 3,400 BTU/hr/HP.
This equates to nominally 160 CFM/HP for a 20Fdeg drop across the exchanger coil.
Maintainence and Service
Hydraulic motion platforms are lubricated for the life of the unit.
Tapered roller bearings are used throughout which are packed when new.
No further lubrication should be required.
Other than cylinder seals and servo-valves literally wearing out, the platform itself should require no maintenance.
It is good practice however, to check components and systems on a regular basis to avoid any potential problems.
Oil in the HPU is continually filtered to three microns and should stay in excellent condition for virtually the life of the equipment.
If it is necessary to “add” oil because of system changes or loss, it is imperative that the make up oil be pre-filtered to three microns before adding to the reservoir.
Periodic checking of the oil level and filter condition is simply good preventive maintenance.
Location Requirements
This all depends on the size of the motion base.
The rule of thumb is to leave a minimum of 30 inches around the maximum excursion limits of the platform.
For example: if the front edge of the motion platform can “surge” forward 20 inches from its park position, then there should be no barriers or walls closer than 50 inches from the front edge of the platform.
This is for both safety and access.
Certifications and Codes
All of the components of the motion system are designed to meet, and in most instances, exceed all known applicable USA codes and requirements.
ASME, NEC, ATM, AWI are typical codes that are followed in the design and fabrication of all motion platforms that we manufacture.
Platforms have been produce using European, TUV and other codes, however that must be specified in order to assure compliance.
Production Time
Typically, motion platforms up to 5,000 pound payload capacity can be produce in 120 days or less.
All production schedules are a direct reflection of the ability of the sub-contract suppliers to produce their respective hardware and provide it to us.
Other quicker schedules can be achieved but at the premium charged by each sub-contract supplier.
Order-of-Magnitude Cost
Typically the cost of electric motion platforms are more expensive than hydraulics systems for the same payload capacity.
The cost of both hydraulic and electric systems are directly related to the payload and performance requirements.
This relationship, unfortunately, is not linear. For example: the cost to produce a 3,000 pound payload electric system is not three-times the cost of a 1,000 pound payload system; it will be significantly more.
An Order-of Magnitude estimating sheet is provided to give the prospective customer a range of costs that might be expected.
What is Included in My Purchase
All of our motion platforms come complete and are ready to operate.
It includes the Motion Platform, HPU (disconnect if it is an Electric System), Computer, Controller and Software.
Once installed, the motion base is ready to operate.
The software includes a Manual Control / Self-Diagnostics application.
Other motion cueing applications can be provided such as:
- Fourier Terms Interface
- Ridefilm Interface
- Telemetry Extraction Interface
- (custom programming is also available)
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