EV Pusher Enhancements

Aside from the obvious task of providing power to move the EV Rabbit from place-to-place, I've managed to come up with an additional use for the trailer.

Recently, I moved after selling my home and used the Pusher to get the EV to the new property, a one-way trip of about 80 miles total. I then hitched the trailer to the rear of my pickup truck, set it up to run at idle (the automatic transmission can't be towed at speed or long distances without the engine running), and returned it to the city which I was leaving. I had another purpose in mind for the Pusher.

Since the Pusher is self-contained, that is it provides all of it's own power, the only thing needed to allow its use on any other vehicle is an extension cable with the proper connectors at each end to interconnect the control head to the control cable on the front of the trailer and the appropriate trailer lighting connector to supply brake, turn and running lights from the tow vehicle.

What I had in mind was a power assist for my old and painfully slow Housetruck, which, in spite of having a 12-speed transmission, dual exhaust and a two-barrel carburetor on a completely rebuilt engine, can barely attain 55 MPH on level ground, given enough time and a tail wind. An additional 52 horsepower would be most welcome, especially when ascending any uphill grades.

Installation was pretty straight forward. I ran a 15 conductor shielded cable from the instrument panel on the truck to the rear bumper and installed the proper AMP connectors at each end. The single connection that the Pusher has to the EV's electrical system is the fuel/temperature gauge in the instrument cluster of the car. Digging through my collection of spare parts, I found a VDO temperature gauge from a VW that would substitute directly, and would be powered by the trailer's electronics. Since the trailer has separate turn and stop lights, I opted to run a dedicated trailer lighting cable from the instrument panel of the Housetruck to the rear bumper, supplying discrete left/right/brake signals for the trailer's lights.

Since I had no way to test the trailer control or lighting until moving day (I couldn't get the trailer up behind the truck because it was backed into a corner of the lot), I had to trust that my wiring was correct that that the trailer would perform property the first time, there would be no allowance for failure once I got rolling on the move.

I must have gotten most of the wiring correct, as when I coupled the trailer to the truck and tested the controller, everything worked as planned. Right up until the time I was ready to pull out the driveway and put the Pusher into "D" for drive, then the engine died. This told me immediately that I had wired the connectors incorrectly and the trailer thought it was in "demo mode". One of the precautions against the Pusher becoming an unguided missile if the engine was started when it's not connected to a tow vehicle is that the original lockout wiring on the shift lever is set up as an interlock to prevent the engine from running when the transmission selector is in either "D" or "R". This is accomplished through wiring differences in the control head and EV's extension cable from the dashboard. When the control head is connected directly to the trailer's cable instead of through an extension cable, the ignition is disabled in any transmission selector position except for "N" or "P", hence "demo mode", meaning that the trailer is safe to start and run as a stand-alone unit, as it can't be put into any gear, which could have interesting results if it wasn't hitched up to something heavy.

At any rate, a few minutes with a screwdriver and clip lead, I had defeated "demo mode", and was on my way. The tow hitch on the Housetruck is quite a lot higher off the ground than the one on the EV, and the attitude of the trailer was much too tongue-high, but nothing that would prevent me from using it on the road.

Here I am, getting under way in the Housetruck for the first time in six years, heading out of the city and off to a new life in the country. For this trip, I had two chase vehicles, and I had set up the first with a CB walkie-talkie so that we could converse while I was on the road.

My first surprise was that the little diesel in the Pusher could move the 14,000 pound Housetruck without assistance. Of course, the acceleration was negligible, but advancing the throttle on the trailer from a stop would cause the truck to slowly move forward. Even before leaving the confines of the neighborhood streets, I found that the trailer allowed me to start the truck off from a stop in second gear direct instead of first direct, which was never possible before. Already, this meant that I would be moving forward with greater grace, as would have at least one less shift of the transmission at low speed.

Out on the freeway, I found acceleration improved to a noticeable degree, and I experienced less lagging during shifting, as the truck was still being powered even when I was holding the clutch in and double clutching while shifting the auxiliary transmission. Overall, the truck now handled like it had adequate power for the first time ever.

Of course, the whole point of this exercise was to see what a bit more power would do to the truck's top speed, so once I came up to cruising speed, I shifted the transmission into fourth gear overdrive. In the past, this gear was only usable downhill or with a strong tail wind, as the truck's engine didn't have quite enough power to keep up with the friction losses and wind resistance, and would very slowly lose speed, even with the accelerator floored. This time, I was able to hold 60 MPH consistently, and the vacuum gauge on the dashboard indicated that the truck's engine was running at a much lighter load than normal.

Not being able to see hear the Pusher, I set the throttle to approximately the same position that I would use to attain 55 MPH or so in the EV, and left the rest to fate. About ten miles out of town on a rural road, Roger called on the radio to tell me that he didn't like the looks of the trailer, that he thought he saw smoke coming from under the hood. About the same time, I saw the temperature of the Pusher's engine begin to climb a bit higher than I was comfortable with. I cut power back and headed for a turn off to investigate. What we found was that nearly all of the coolant had escaped from the reservoir's pressure cap and sprayed all over the engine compartment. This was the "smoke" that Roger saw. Under the hood of the trailer were ten or so containers of bottled drinking water from one of the previous trips to Solwest, so we began twisting off caps and pouring the water into the reservoir. The coolant level came up with no apparent leaks, and the engine temperature went down. I decided to press ahead using a lower setting of the trailer's throttle. My reasoning was that the Housetruck was presenting a large wind block to the trailer and perhaps it wasn't getting enough cooling air through the radiator.

Once back on the road, I had an additional thought. The accelerator cable on the Pusher runs through a lever on the automatic transmission for the purpose of regulating shifts of the gears. I had never quite gotten this adjusted properly, and when using the trailer on the EV, I have to remember to lower the throttle position manually for an instant in order to make the transmission shift into third gear. Since I hadn't done this because I can't hear the engine in the Pusher in this application, I was probably hauling along at 55-60 MPH in second gear on the trailer with the engine wound up tight in RPM's. This could account for the overheating and spewing of coolant (some weeks later, after arriving at my destination, I found that the V-belt driving the water pump was loose, which probably contributed to the problem).

At any rate, I kept the throttle position lower for the rest of the trip, increasing it only when needed to provide additional power for hill climbing.

The first test of that occurred at Badger Mountain Pass, a small but fairly steep grade in the foothills of the Coast Range. During all of my other excursions involving this pass, I found that the truck would crawl up in second gear at 15-20 MPH tops. With the assistance of the Pusher, I was able to stay in third gear and hold a steady 30-35 MPH all the way top the top. The Pusher added value to the downhill side of the pass by providing additional engine braking to keep the speed at a manageable velocity.

I made a stop in Walton to check the coolant level and allow traffic to pass, as there would be no passing lanes for the next 15 miles or so.

The only other significant grade was before the Peterson Tunnel, where I purposely let the speed drop below what I would be able to maintain to allow traffic to pass again before entering the tunnel. It's not that I was holding up a lot of cars, on the contrary, I was able to keep my speed up to the legal limit of 55 MPH with spurts to 60 MPH on the level straightaways, but this highway is a commuter corridor, and no matter how fast you drive, there will always be someone who wants to go faster. I'd much rather have those drivers ahead of me than behind.

No other unusual events occurred. I probably could have used the Pusher to supply more power than I was attempting once I had figured out that the transmission needed help shifting into third gear, but the trailer was doing the job I needed, which was to make my job of moving the Housetruck to it's new home less stressful. Now that the umbilical control cable is installed on the truck, I can use the Pusher any time I decide to move the truck. Who knows what additional uses I'll find for it.