Electric Lunch
Combat robot

Electric Lunch is a robot I built during the Winter of 2000/2001. originally the robot was to have 4WD and a lifting arm for a main weapon. The weapon would be able to lift an entire Super Heavy up to 3 feet high if necessary and it would give the robot the ability to self right if it was inverted. Well as things sometimes go I built the drive train and was happy with its performance. Then I built the lifting arm. Unfortunately in testing I broke the drive motor for the lifting system by jumping on the forks with my 250 lb butt to test it for strength. I could not afford to replace to motor. So in total frustration I built a pushy bot. This page will describe the drive train that is really all this robot has for a weapon.

The drive train is laid out to provide 4WD with redundant drive for each side. The drive chains are configured in a Bow Tie arrangement. If you look at the center shaft from a side view the shape of the chains sort of resemble that piece of apparel. The bottom frame is a base plate design that is made from 3 foot square 1/4 inch thick piece of 6061 T6 aluminum

The drive motors used for this robot are the venerable Bosch 750 W 24 VDC permanent magnet motors. The motors produce about 1.2 H.P each. This is not a lot of power for a Super Heavyweight. Knowing this I had to compensate for lack of motor power by using a lot of gear reduction. The motors are supported by a face plate welded to angle iron. This plate is bolted to front of the motor using the mounting studs provided. The rear of the motor is supported by a 4 inch Steel automotive muffler clamp welded to a piece of 1 1/4 inch angle iron. The angle iron has slots cut into it for sliding the motors forwards and backwards for chain adjustments.

The motor power is connected to a jack shaft using #35 chain with a 4.5 to 1 reduction. The power is then sent to the drive wheels with a 2.5 to 1 reduction. The total gear reduction is 10.8 to 1. This gives about a 400 rpm axle speed and the robot is capable of about 10 mph. Using this low gear ratio allows the robot have an acceptable amount of tractive power, although I would like a lot more. In a pushing fight you really need as much power as your tires can hold. This robot will just break its tires loose if placed against something solid like a concrete wall. So it's power to weight is pretty close really for the tires being used. (Smoking your tires will not win a pushing battle).

The drive wheels are all mounted on live axles supported by pillow block bearings on both sides of the wheel. (this is called a double shear mount). This is probably the strongest way to mount a drive axle. The axle shafts are 1 inch shafts with a 1/4 inch key way cut the entire length of the shaft. The pillow block bearings are di-cast they are made from a material called Zamak which is a zinc alloy. They are stronger than cast iron pillow blocks because they resist cracking and they are much lighter. They were all purchased from Graingers. The pillow blocks are mounted on 1 1/2 high angle iron brackets that is welded to a piece of 1 1/2 flat bar to provide the correct ride height. The flat bar is slotted to allow for sliding the axle forward and backward for chain adjustment. I always allow enough adjustment for 1 chain link in both directions. The brackets are mounted to the base plate with 3/8 inch by 1 inch long grade 8 bolts and held from slipping with self locking serrated nuts. Except for 6 bolts in this robot all of the bolts in this robot are the same size. That way I only need one  9/16 inch wrench or socket to tighten about everything. It's a KISS thing...

The Blade weapon. This weapon is not a true wedge its more of a pusher and a shield. The blade is made from 1/4 inch thick mild steel. It started life as a 38 inch wide by 16 inches tall plate. It was formed using a large rosebud heating torch and a 8 lb sledge hammer. This was sort of hard to do because the plate is so wide it's difficult to heat its entire length. It took a lot of pounding with the big hammer. actually we talked to one of the neighbors about our welding and grinding noise at night. He said that didn't bother him. But he said "What the hell were you doing the other night at 10:00 PM" Well we were bending this plate and the sound was echoing through out the canyon. It sort of sounded like gunshots to me. He He.  :)
Recently I coated the entire edge of the blade with Hard facing welding rod this resists bending and gives the edge a hardness of  50 Rockwell (C). It's pretty tough.

The blade is attached to the base plate with a sub frame. The main supports for the blade consist of  four 1 inch schedule 40 Steel gas pipes. They are attached to 1 1/4 inch angle iron that is bolted around the entire base plate. Adding this frame really strengthened the base plate and removed a lot of flexing. This frame also provides the mounting points for the 1/8 inch thick Aluminum diamond plate box that covers all of the internal parts..

Parts suppliers for Electric Lunch
Graingers
MSC
Northern Tool
Kaman
Lowes Hardware
Sacramento Electronics
Reno Salvage
Team Delta
Quincy Auto supply
NAPA Auto parts

Our thanks to all of our parts suppliers for their help, support and patience..
 

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