Converting a telephone truck to electric
|Ful electric telephone truck|
Old telephone trucks make a great tool for cleaning gutters, painting, siding and many other uses. I converter my 40 year old truck to full electric, this blog which starts at the page bottom follows the conversion process.
First zero carbon test drive
For the first test ride, I clamped on an amp meter, and took my first ride around the yard, up some hills, tried first, second, third gears. In first, the average current draw was in the 60-75A range, it climbed hills with no more than 150A, and it even started off in third gear from a stop.
|EV telephone truck is ready to get to work|
I need amp and voltmeters before I get better data.
Don't need the 6:1, this configuration has more power than required for my around the yard moving of the machine.
The bucket has dual controls, one set in the bucket, a second on the end of a 20 foot cable so the boom can be used as a remote crane. The boom hydraulics run off a 36V golf cart motor. The 55V solar panel array will keep the battery's charged and ready to go.
It would be great to make a remote steering and motor control system in the bucket, so I could ride around up there. It would get pretty hairy with the boom at it's 25 foot level. The thing crawls at very low speed, so it would be possible in theory.
The hydraulic boom could let the solar array track the sun, bigger array?
Too many projects, not enough time.
For now,the EV telephone truck is ready to go to work.
(Posted 7/5/2008 by mikey)
E-Tek motor drive installed
Made a motor mount weldment and got it attached to the rest of the motor drive system.
|new motor mount with chain reducer|
A careful use of an angle iron and some clamps assured that we welded the motor bracket to the rest of the assembly with perfect chain alignment.
After tacking the parts in place, I had to remove the whole weldment to finish all the welds and check alignment. I used the 4:1 reduction,since the smaller 12 tooth sprocket which will yield a 6.6:1 reduction has not arrived yet.
I wired in the bucket hydraulics, and solar charging system, so my full electric solar recharged bucket truck is 100% operational YEA!
(Posted 7/4/2008 by mikey)
New coupling shaft
The big motor was removed, saw blade was disassembled from clutch plate. The clutch plate rivets were ground off, and the central torque plate was removed. A look through my stuff pile turned up a rusty cast steel pulley with a large enough diameter, and 1-1/8" bore. The shaft was turned down to make a press fit into the pulley, and the pulley was welded to the shaft.
|new adapter shaft|
The pulley was turned down with a precise cavity on the mounting end so the torque plate self centered when placed in the cavity. The 20 holes were used as guides for drilling and tapping 10-32 holes. Ready to mount the bearing.
(Posted 6/30/2008 by mikey)
Not enough torque
After getting the electric drive components and battery connected, I found that the brakes and wheel drums were frozen, and the wheels could not rotate. I removed and freed up the rear brakes, and got the wheels to rotate freely. The front disk brakes were also frozen, so they were disassembled and made to work with much difficulty. The splitter valve for the brakes was broken, and the master cylinder had a vacuum leak.
|4:1 additional reduction|
When all was said and done. I routed the master cylinder output directly to the front drivers disk brake assembly (the only one that worked). The first electric run was disappointing, as the motor running with the max 400A that the controller is capable of, was just able to push the truck on flat grass. Once I tried to climb even a slight hill, it just gave up.
Based on the amp/torque curves for the CM77 motor, I should have been producing about 37 Ft Lbs. The CM77 output shaft is not designed for side loading, so it is not a good option for a chain based torque magnifying system.
I purchased an 80 tooth chain sprocket, a 20 tooth, and 12 tooth smaller sprocket and a bearing so I can make an additional chain speed reducer.
The e-tek motor running at 200A produces ~19 ft lbs, so if I use the 12 tooth drive sprocket with the 80 tooth large sprocket, which is a 6.6:1 ratio, I should be in the 125 Ft lb range which I estimate should be sufficient to move the 8,000 lb truck around my yard.
I may be able to walk faster than it will move, but thats fine for around the house.
Why is it never easy?
(Posted 6/2/2008 by mikey)
The next step was to mount the batteries and controller and wire it up. I bought some new batteries, as the 12 T105's that I had were pretty beat from to years of golf cart use. The batteries were mounted on an angle iron frame that was welded to the frame.
|All wired up|
I got some beefy battery terminals, and invested in the correct crimping tool for the big 2/0 wire that was used for the high current wiring. $4.75 a foot for the welding cable makes one very careful to use as short a wire as possible. The throttle pot and linkage is always an expensive item, so I decided to try a simpler cheaper way. The truck throttle cable was fed through an aluminum bracket, and then to a spring to pull the cable out and lift the throttle pedal.
The travel of the pedal/ cable was limited by a small aluminum bracket so the cable travel is the same as the 5K slide pot travel. I found a piece of thin spring steel with a slotted end, that with a bit of sanding fit nicely into the slot in the slide pot actuator. The slide pot was moved to the end of travel, and the throttle switch adjusted to open when at the end of travel. The spring steel actuator was first held with zip ties, then taped to the throttle cable sleeve with black electrical tape, which is carefully coated with PVC pipe cement to make it permanent.
It works quite well considering how simply it is made. The first powered test showed a non linear response, and sure enough the pot was an audio taper rather than linear. I mounted the pot so the taper gave smooth low speed operation, and a fast ramp up in speed at the full throttle end. The worlds first log throttle.
(Posted 4/25/2008 by mikey)
The mounting plate
The broken terminal strip was replaced with a new one machined from a piece of linen phenolic that I had. I pressed in large brass nuts, then glued them in with epoxy. The next issue was the strange mounting system. The motor was designed to fit a cast iron mounting flange with a bayonet lock and keyed anti rotation section. I chose an easier to make 1/2 " aluminum plate, and a bayonet ring of just the right thickness so I had to tap it with a hammer to lock it in. A separate steel keyed block was made that bolts to the large aluminum mounting plate. The bell housing looked a bit weak to support the 90 lb motor, so I welded up a complete angle iron bracket to carry the weight.
|Motor mounted and ready to go|
I clamped the bell housing on my bridgeport table then indicated the round tranny locating hole on the bell housing to center the miller quill on the tranny mounting hole.Then I took the main motor mounting plate and with the indicator got that exactly concentric with the tranny hole. With the plate clamped to the bell housing I drilled two spring pin holes and drove in the spring pins to allow disassembly and re assembly with perfect alignment. I transfered the two 7/16-14 holes to the mounting plate and drilled clearance holes.
The final step was to determine the exact thickness spacer necessary to engage the clutch plate with the tranny spline with about 0.02" clearance between the two shafts.
With some help, the assembly was mounted. Next step battery holder.
(Posted 4/9/2008 by mikey)
The tranny has one size spline, and the motor had a slightly smaller spline, so rather than spend a lot of time and money trying to find an adapter, I decided to use the clutch plate which already mates to the tranny shaft, and adapt it to the motor output shaft, using a steel disk. While a 10" to 12" saw blade would do the same job, I found some larger blade blanks that I had been given by a friend, and decided to use that.I punched out 10 of the outer rivets on the clutch plates, opened the holes to the tap drill size for 1/4-28 screws.
|Drive shaft is coupled to clutch disk|
I turned a snug fitting steel alignment shaft that fit on the ID of both the clutch disk spline and the saw blade ID. This forced the two disk to be centered on each other. I clamped the two disk together, and drilled the tap drill holes through the blade. The blade holes were tapped to 1/4-28, and the clutch disk holes were opened to 1/4". The motor output shaft was welded to the saw blade, and the clutch plate was screwed to the saw blade to make the final adapter. The assembly was spun in a lathe to confirm that it runs true. Now the delicate and critical final step of mounting the motor to the bell housing exactly concentric with the tranny output shaft. Both the tranny output shaft, and the motor output have some degree of shaft misalignment compensation which should help.
(Posted 3/31/2008 by mikey)
The drive motor
This Truck is pretty heavy, and even in first gear, it takes some serious torque to move it. My first motor choice was the e-tek which is a PM motor, but after looking at the performance curves, it really would be pushing the e-tek to try and drive the truck.
|The power plant??|
Back in the 70's I got the bug to build an EV, and picked up a pretty beat 30V 400A 15 HP motor/generator from a surplus equipment company. This is a series wound motor that can take some serious power, so I decided I would use that instead. These motors have so much torque that the drive shaft can snap, so they use a torsion bar output shaft. The rear of the torsion shaft is driven by the rear female spline of the main motor shaft which is a tube.The output side of the motor has another external spline to drive the drive flange. The flange elongated slots engage the three raised post on the output end of the torsion shaft once the torque is high enough.A clever way to keep the output shaft from snapping under the high torque.
The drive spline will not be used on my coupling system so I cut it off with an air cut off wheel, since the shaft was too hard to cut with a bandsaw.
(Posted 3/31/2008 by mikey)
The tranny needs to be supported on the frame, so I bent a piece of 1/4" X 2" steel angle iron to the required angle to screw to the top 3 bell housing mounting screws, and terminate flush to the frame members.
|mounting the tranny|
I cut out two shorter angles, and screwed them to the tranny mounting angle at both ends. I welded a nut on the rear of the short angles so the 3/8-16 bolts would have a real nut to screw through.The two small angles were then welded to the frame. The extra drive shaft was cut off to keep the electric motor from needing a thick spacer when mounted to the remaining screws in the bell housing. The clutch plate will be my final drive attachment to the motor shaft, so I needed a disk to make the final connection to the drive motor. I had some circular saw blanks, and will see if I can make it work with a bit of machining and welding.
(Posted 3/28/2008 by mikey)
Bucket truck kicks it's gas habit for good
I picked up an old telephone truck some years ago, and have found it very useful for many things. Painting, cleaning gutters, lifting shingles to the roof for roofing, trimming branches, as a crane with my remote control. The Onan gas engine that ran the hydraulics for the lift ran dry one day and seized up, so I mounted a golf cart motor in its place and mounted 36V of batteries with a solar charger, converting the lift to full electric. It works great, always ready and charged. The truck has a big V 8 engine in it, and as you would expect with an engine that hardly ever runs, it is a major chore to get the V8 to run whenever I want to move it.In preparation for a lot of roof level projects that will be coming up on the to do list, I decided it was time to finish the job, and convert to full electric. No need for road travel, just need to move it around the house, so I figured I would pull out my spare E-tek motor and controller, and start there. Troy, and Dan came over and we got the gas guzzler out of the beast after a bit of wiggling.Now I need to support the tranny and motor, couple the e-tek to the motor, do some wiring, and hopefully I should be able to ride around the yard in first and reverse.
|EV bucket truck conversion 1|
(Posted 3/23/2008 by mikey)