As we continue the Reding Electric Vehicle build, our team encounters a few hurdles for which we have to assemble students from other disciplines to help research, test and refine solutions to various aspects of our new motor vehicle...
Firstly, the team discovered that upon initial test drives, the REV's drive chain tended to fall off the gears when coasting on a downhill.
By grabbing slow motion video of the incident, we narrowed down the tendency of the chain to gain slack on the trailing side when coasting downhill. With our team in action, students took to the Tech Design room to design and build a "slipper-type" tensioner assembly made of 3D printed PLA material.
Once a few versions of the slipper was created, we bolted the item together and installed it on the slack side of the chain, to keep it tensioned under acceleration and coasting. The chain has not fallen off since the tensioner was added, so Team REV chalks up another win in design!
Also, we found the REV's top speed could not get past 9 km/h. With some brainstorming, our class surmised that the gear setup was too "tall" for the electric motor's torque. So, with some further thoughts, we came up with a small single gear transmission, placed in between the motor and final drive gear.
This gear reducer on a shaft allowed the motor to work with less strain, ultimately getting top speed up to Mr. Ford's original top speed of 10 mph, or 16 kph!
It was time for Mr. Lograno's grade 10 Science students to enter the class and put their knowledge of parallel and series circuits to use. Their job was to find a way to orient the vehicle's four 12-volt cells in order to power the 48-volt drive motor, while still safely powering the REV's 12-volt headlight and 12-volt horn-buzzer without overvoltage. After drawing up schematics under Mr. Lograno's supervision, they then built the circuits with proper gauge wiring and connectors.
And upon flicking the proper switches, all three loads were working by the end of the research session- lights, buzzer, and motor action!
Another grade 10 student took to the wood shop to help create a drawer-type slide system for the vehicle's power cells. Built on sliders, the battery tray will allow easy access to the REV's batteries for service and replacement.
With several issues now being solved, we kicked into research mode again, and had Mr. Piva's grade 9 Mathematics students gather real-time data on motor speed and drive wheel RPM to validate the proper speed expectations of the REV. By their calculations, it has been confirmed that the REV and it's little 2 horsepower electric motor can clear Henry Ford's 10 mph initial top speed!
Students now worked on completing the carpeting of the REV's driver's seat, gluing black carpeting into place before securing its edges with decorative tacks.
Another student then took the laser etched dashboard and drilled the accessory holes before fitting the toggle switches and voltmeters into place, so that the driver can monitor cell voltage during leisurely drives.
Our AP Engineering student worked on incorporating a speedometer feature into the radar proximity warning system, debugging the code entered into the Arduino based CPU, before soldering final connections to be placed in the REV.
Finally, Mr. Da Silva and the grade 12s, noticed that the initial relay-driven cell isolators were a bad idea, becoming too hot to carry current from cell to cell. So in it's place, a manual isolator system was employed under the driver's seat, to help place the REV's cells OUT of series mode so that they can be charged by a 12-volt charger.
We see the reveal deadline of June 4th is fast approaching, so team REV will now sprint hard to the finish line to give the Reding Electric Vehicle final touches and a good coat of stain and varnish before the reveal.
See you soon!
