Frequently Asked Questions
1. Can I obtain specifications for the Pittman Motors used in the GEARS Invention and Design System kit?
Yes. All stock Pittman gear head motor specifications can be found on the Penn Motion Industries website.
The Pittman motors provided in the GEARS Invention and Design System kit have 15V custom windings. For this reason they are not listed in the manufacturer's data sheet. The windings are GM9X34 series windings and therefore much of the published information can be used to extrapolate the necessary information for a 15V winding. For your convenience, the basic winding data is listed below. Both the manufacturers published specifications and our own experimentally determined specifications are listed:
Stall Current = 12.06 Amps @ 15.1 volts (Manufacturers Specs) = 0.8 Amps/Volt
Stall Current = 9.7 Amperes at 12.5 volts (Experimental ) = 0.76 Amps/Volt
KE Voltage constant = 2.43 volts/Thousand RPM (Manufacturers Specs) = 0.0232 volts/rad/sec.
KE Voltage constant = 2.43 volts/Thousand RPM (Experimental) = 0.0232 volts/rad/sec.
KT Torque Constant = 3.21 oz-in./ampere (Manufacturers Specs)
KT Torque constant = 3.02 oz-in./ampere (Experimental)
2. Can I use motors other than those provided with the GEARS Invention and Design System kit?
ABSOLUTELY YES. The GEARS-IDS kit was conceived by an educator frustrated with the constraints imposed by toy-like kits that used tiny, proprietary plastic parts that are incompatible with real world engineering components and nearly impossible to replace when they are lost and broken. The GEARS kit provides users with the option to choose the engineering components they want and need from hundreds of different distributors and surplus vendors worldwide. There is a wide assortment of gear head motors and servos to choose from and here are some tips to consider when making your choice:
Selecting Motors; The 2 channel electronic speed controllers (ESC) provided with the GEARS-IDS kit are built to control fixed magnet brush commutated DC motors. These ESC's can handle up to 144 Watts of intermittent electrical power Since Watts = Volts x Amperes, it is necessary to choose a motor that will not draw significantly more than 144 Watts when stalled. Manufacturers of quality industrial motors like Pittman, publish the electrodynamic performance characteristics of their motors. The published data includes among other things the stall current of the motor at a given voltage.
Download a GEARS-Educational Systems Lesson (700kb .pdf file) that illustrates and explains terms and concepts involved in selecting brush commutated fixed magnet DC motors. GEARS Educational Systems is committed to partnering with suppliers and vendors who make engineering education resources available to our customers.
Note:The GEARS-IDS kit contains heavy duty motor mounts with industry standard bolt hole patterns compatible with all 8000, 9000 and 14000 series Pittman gear head motors. Motors manufactured with these standard mounting patterns are available through online retailers.
3. Can I obtain specifications for the Batteries used in the GEARS Invention and Design System kit?
Yes. The battery included in the GEARS-IDS kit is a 12 volt, 1.2 Ahr, VRLA (Valve Regulated Sealed Lead Acid Battery) manufactured by B.B. Battery Corporation.
View the engineering specifications for all VRLA batteries manufactured by B.B. Battery Corporation.
This technical manual is a valuable educational resource. Students who learn to access and use published battery data develop a deeper understanding of electrical power and energy terminology. Moreover students who can read and use technical manuals have the opportunity to develop BOTH the technical literacy and the hands on experience needed to understand and appreciate the engineering challenges posed by emerging technologies like electric and hybrid transportation systems, alternative energy production and the limitations imposed by electrical energy storage systems.
4. Why did GEARS choose 12 Volt VRLA batteries for use in the GEARS Invention and Design System kit?
The choice to use a 12 volt system was predicated on the fact that many engineering components using DC current require either 12, or 24 volt power. Readily available items like communications equipment, chip cameras, video transmitters, electrical actuators and sensors operate on either 12 or 24 volts DC. The manufacturers of the GEARS Invention and Design System chose VRLA batteries because they are easily and inexpensively scaled to nearly any engineering power demand. Unlike more expensive battery chemistries that need to be carefully managed, VRLA batteries are easy to maintain and can be recharged immediately after each use without suffering from "Memory" effects. 12 and 24 volt VLRA battery packs are available in virtually any Ahr rating. VRLA batteries are the most economical choice with respect to cost per Ahr and it is easy to create dual 12-24 volt "On-board" power supplies using 2 identical 12 volt VRLA batteries.
GEARS Educational Systems creates and sells products that offer the users the greatest possible design latitude. For that reason we encourage our customers to purchase batteries and additional engineering accessories from brick and mortar and online vendors who are convenient to use and who offer the best possible value....and we build our components rugged enough to support the engineering components you choose to use!
Finally, it is important to note that BB Battery Corporation will accept any BB battery for recycling.
5. Can I obtain engineering data for the Deltran charging system used in the GEARS-IDS kit?
#6 Can I charge more than one of the GEARS-IDS 12 volt batteries at a time using only one of the chargers included in the GEARS-IDS kit?
Yes. You can use the battery charger included in the GEARS-IDS kit to charge two (2) 12 volt sealed lead acid batteries simultaneously....without having to purchase an additional charger!
View a circuit description that will allow you to charge 2 lead acid batteries simultaneously.
The GEARS-IDS charger is sized to accommodate the charging of (2) two 1.2 amp hour batteries simultaneously at approximately 3/10ths C.
- Do not charge more than 2 lead acid batteries simultaneously
- Do not charge batteries of different capacities at the same time.
- Charge only lead acid battery chemistries rated at 12 volts
7. Can I use the Deltran charger supplied in the GEARS-IDS kit to charge larger capacity batteries?
Yes. However, it is important to remember that the charger algorithm is only suitable for lead acid battery packs.
The charger included in the GEARS-IDS kit is a 3 stage charger that charges at a maximum rate or bulk charge rate, of 0.750 milliamperes. You can easily approximate length of time needed to charge a lead acid battery to 80% of full charge. Simply divide the nominal battery capacity by the charge rate. Example: The batteries supplied with the GEARS-IDS kit are rated at 1.2 amp hours (1200 mAhr). Therefore the charge time needed to bring a dead battery(approximately 10 volts)up to 80% capacity is 1.2/0.75 = 1.6 hours or 6/10ths C. It is expected that users of the GEARS-IDS products may choose to use a 12 volt lead acid battery of larger capacity, or charge up to 2 12 volt batteries simultaneously, with a combined capacity of, say, 4 amp hours. In this case, it would take 4/0.75 = 5.3 hours to bring a dead battery to 80% charge. This would be a charge rate of nearly 2/10ths C. Sounds like a long time. But the advantage of lead acid batteries is that they can be placed on charge and kept on charge immediately after each use without suffering "Memory" or capacity losses. In fact, lead acid battery life is enhanced if they are charged early and often between discharges.
(Note: Charge rates are not linear as the battery nears full capacity. In fact it can take up to 50% of the total charge time to effect the last 20% of full charge capacity!)
8. Are the GEARS-IDS components compatible with standard hobby RC radios and servos?
Yes, the GEARS-IDS system is fully customizable. We want students and teachers to have the design flexibility to use RC equipment from a variety of manufacturers, and the freedom to choose the equipment that best meets their design requirements. Some mechatronic designs need only three channels of control while others may require 7 or 9 channels. The GEARS-IDS system is deliberately designed as an "Open" platform. In fact we encourage educators and students to incorporate as many real engineering components and "found" items as possible in order to "engineer" solutions to the design problems and inventive opportunities they create. We believe that a ruggedly built, universal construction platform intended for indoor/outdoor use, provides the most creative opportunities for engineering education.
Below is an example of a grasping manipulator that was fashioned by cutting 1" inch strips from a short section of a 10" diameter PVC pipe that was leftover from a local road construction project.