Monday, July 22, 2013

SuperTruck: Steering

So how DO you steer a DIY hybrid pickup truck without the engine on? That’s just one of the many challenges to figure out while working on a DIY project. In general, most cars nowadays use power steering. Power steering uses a hydraulic pump to assist turning the wheels, and that pump runs from a belt connected to the engine.
The downside is that if the engine is off, so is the power-steering. And on a hybrid where the engine may or may not be on, that’s not a good solution.
So what are the options?
One thing I’ve heard people do is that they use the power steering, but disconnect the belt from the engine. The two hydraulic hoses are then looped to each other. This essentially converts the power steering to manual. However, I’ve also heard of mixed results this way and the actual gear ratio inside the power steering box may NOT be ideal for manual steering.
One slick way to go is to use an ELECTRIC power steering pump. On this system, you have power steering, and it doesn’t care if the engine is on or not. The power for the pump comes from 12V DC, instead of a belt running off the engine. It’s a great solution for a hybrid, but I did a quick web search and was surprised at how pricey they can be!
DIY Electric Power Steering
I suppose one way around the cost of buying a commercially-available electric power steering unit is to build it yourself. This would require adding a 12V DC electric motor that would spin a pulley, connected to a belt, connected to the original power steering pump. The down-side is buying a motor, designing it all, and the extra weight and space it would take up.
Back in the days before power steering, MANUAL steering was all the rage. You simply turned the wheel and it mechanically rotated the front wheels left and right. The gearing was such that you might have to spin the wheel a few times to turn the wheels all the way and yes, it may have been a bit more work than modern power-steering, but it worked just fine.
So what’s the BEST way?
To me, the best is OFTEN the simplest. My current thought is that the best way to convert the steering in the S10 for hybrid use is to swap the power-steering gear for a manual gearbox. Of all the options, it uses the least space and weight, and is the simplest. The truck will drive the same whether the engine is on or not. It also doesn’t take any additional energy. Some of the electric power steering units can draw up to 50 amps!
Of course the downside is that it’s manual steering. It may take just a bit more arm strength to make a complete turn at slow speeds, such as in a parking lot. On the other hand, my Electro-Metro has manual steering, and I’ve always liked the way that car drives!
So, as of right now, I’m planning on pursuing the manual steering swap. I already have the S10 manual steering gear. As far as I can tell, all of the second generation trucks (’94 onward) had power steering. However, about a quarter of the first-generation trucks (’82-93) had MANUAL steering. Both steering boxes have three large bolts that mount them to the frame of the truck. Looks to me like the two different steering boxes are completely interchangeable.
How about you? Have you ever swapped out typical power steering for something else? What did you do and how? Why did you do it? For more power, or some other reason?
If you have any great power-to-manual steering tips, tricks, ideas or stories, send them my way! I’d love to here ‘em!