inline driveshaft motor?

[orange4boy]

So just on/off like my Auranthetics? Crude but workable. I always wish I had this for crawling traffic.

How about the simplest thing ever... a lever engaged spring loaded tire powered by an electric motor that runs on one of the rear wheels like so many fair rides. Saves the geometry issues that the Insight extra wheel motor has. Just up and down to worry about.

[Christ]

Originally Posted by orange4boy

So just on/off like my Auranthetics? Crude but workable. I always wish I had this for crawling traffic.

How about the simplest thing ever... a lever engaged spring loaded tire powered by an electric motor that runs on one of the rear wheels like so many fair rides. Saves the geometry issues that the Insight extra wheel motor has. Just up and down to worry about.

That would work out too... in my design for Cara, which will probably never happen due to other thoughts taking prevalence, is just a non-reversible motor with an over-running clutch, connected to the axle's input by a CV shaft, with a simple high-voltage contactor to turn it on/off, limited only by the voltage input. No soft start, no regen, etc.

In this way, with 5 HP (approx) I should be able to do the lower speed sections of town, at least in the flat areas, at 20MPH or so. Most days, this would be perfectly fine. IIRC, I'd need about 7.5 - 8HP to keep me going 30MPH even on slight hills, which is exactly like driving through town around here. The other plus is that it's great for pulling away from red lights and stop signs, so no more (start, idle, put it in gear, go) maneuvering, and the availability of FAS up to a light, then hybrid starting off a light (except if you have an auto that won't pop-start).

[bluetwo]

Just thought I'd throw it out there that reversing an electric motor is as simple as reversing the polarity. Meaning, swapping the positive and negative wires, in so doing the motor will spin backwards with the same power and torque.

Anyone who's really smart on this stuff stop me if I'm wrong though, by all means and I know it gets way more complicated when you're talking about the more sofisticated motors like in todays hybrids.

[Christ]

Originally Posted by bluetwo

Just thought I'd throw it out there that reversing an electric motor is as simple as reversing the polarity. Meaning, swapping the positive and negative wires, in so doing the motor will spin backwards with the same power and torque.

Anyone who's really smart on this stuff stop me if I'm wrong though, by all means and I know it gets way more complicated when you're talking about the more sofisticated motors like in todays hybrids.

This is true in several cases, but I've proven it untrue in several cases as well.

For instance, I have a drill motor that will run in reverse, but it will die running in reverse as well.

Backstory - I've used a 12V drill motor wired to a car battery (via alligator plugs) for years now. It's always been reliable, never had a problem with it. I built one for a friend of mine, as well, because it's a much longer lasting setup, with 0 charging time (in most jobs).

When I built his, I accidentally switched the colored clips, so that black was actually positive, and red was actually negative. This was a brand new drill, which had been tested on a normal battery only. Instead of letting me switch the clips, he just reversed the motor gear (reversible drills have transmissions, they spin the same direction either way.), so that he was hooking up the leads red to positive, and black to negative, and then using reverse for forward, and vice versa. About 2 hours later, the drill wouldn't run, and had finally let out the magic smoke.

I never thought reversing a motor would cause this to happen, so I rebuilt the drill... sure enough, it happened again, with the new motor.

Moral: Not all motors are reversible. The ones that are make nice brakes, though, such as those which are normally used in forklifts. Reversing the polarity on those motors (which are specifically designed for this, as they reverse polarity to move in reverse) will act as a brake. The more current you apply, the faster you stop, up to the maximum rating of the motor.

[bluetwo]

Wow... that's a lot of info to take in. Transmissions and whatnot... I'm glad you took the time to type it out and share it though because I'll look it up some other time and try to understand it better.

I learned about reversing polarity on a printing press I worked on years ago. Come to think of it, I wonder if printing press motors would work in any kind of practical application any one of us might try to use. Maybe it's something to think about, maybe it isn't. A new idea nonetheless.

[Christ]

I have no idea what kind of power print press motors are capable of, honestly. I had a chance at a 7HP 240V AC motor, but the thing was like 250lbs easily. All cast iron construction, must have been put together in the early 40's LOL.

Oh - I see you changed your post... I wondered if it was really something to think about or not...

[bluetwo]

Originally Posted by Christ

Oh - I see you changed your post... I wondered if it was really something to think about or not...

Ha ha, I guess redundancy is hard-wired into me from so many years in the military. I didn't even see that I had done that until after I posted it.

[droptail]

Let me just address your first (2) paragraphs.

"I'm speaking about removing the rear driveshaft and mounting the e-motor inline with it. You'll be driving the rear axle with both the gas engine and the e-motor, or just one or just the other, depending which way you want to run at a given point in time".

I get all these options with my proposed plan, with the added benefit of:
1) Being able to remove the motor from the driveline altogether.
2) Have a gear reduction as an option for low speed use.
3) Not subjecting the motor to suspension abuse.

"If you were to mount it as an input to the xfer case from the front axle's output, without it driving the front axle, you'd get nowhere, unless you're in 4wd Hi or Lo, which presents it's own particular set of problems, specifically the inability to shift on the fly (back into 2wd mode), the inability to exceed 45 MPH (not recommended in 4wd Hi, either), and the specifically shorter gear ratios assigned when in any 4wd mode".

Not sure where you get your information or assumptions.
The only time "I'd get nowhere" is if xcase is in neutral. Otherwise, I have (2) motors from (2) different drives to select from, separately, or in combination as mentioned above, (with added benefits). 2Hi is another option I have that you omitted above.
No "particular set of problems" here. My truck shifts with no restriction, on the fly.
45mph in 4Hi not recommended by whom, you? I don't think many would buy a domestic full size 4x4 if the manufacturer made such limited recommendations. Perhaps 4Lo, but that would be from an rpm limit, not gears.

I'll stop here.

[Christ]

Have you actually checked to verify that you have front output when in 2HI mode? Most tcases do not.

The 45mph recommendation is a NHTSA/Auto Mfr recommendation based on the fact that if you needed 4wd, you probably shouldn't be going more than 45mph anyway, not to mention that tire slip increases at higher speeds, and true 4wd systems don't steer well when in use, thus making a very dangerous situation at higher speeds. It's just plain unsafe, and there is no discussion necessary on that topic.

The shorter ratios, I was wrong about. They would mean nothing in your case, since you're driving on a 1:1 ratio from front to rear output shafts.

In most cases, 4Lo is not recommended for use on any surface that isn't soft. As such, you shouldn't be outside of low gear when using it.

These really shouldn't have to be discussed... talk to a few offroaders that have had to limp home on FWD only, and you'll figure out that they're practices that should be adhered to fairly well.

The speed limitations for 4wd mode don't apply if you're using the motor in place of the front axle connection, because you won't be turning all 4 tires under power, so you can disregard that part.

Mounting the motor inline with the rear driveshaft DOES NOT subject it to suspension abuse. I'm not sure where you came up with that...

Using that configuration would also allow you to remove the motor from the driveline by removing a few bolts and replacing the original drive shaft... not sure how hard you think that is, but if you find it difficult to R&R a driveshaft with a carrier bearing, you probably shouldn't even be thinking about this type of mod.

Mounting it from the front input of the xfer case does not give you a "gear reduction for low speed use." as you'll be driving the rear shaft at a 1:1 speed through the xfer case, no matter what gear you're in, unless you have two differential sizes in the front and rear axle, which is highly unlikely. If both axles have the same differential speed, you'll have the same 1:1 ratio in the t-case no matter what range you select, as this is the nature of 4wd... turn front and back so they match each other based on the engine's input...

[droptail]

Originally Posted by Christ

Have you actually checked to verify that you have front output when in 2HI mode? Most tcases do not.

The 45mph recommendation is a NHTSA/Auto Mfr recommendation based on the fact that if you needed 4wd, you probably shouldn't be going more than 45mph anyway, not to mention that tire slip increases at higher speeds, and true 4wd systems don't steer well when in use, thus making a very dangerous situation at higher speeds. It's just plain unsafe, and there is no discussion necessary on that topic.

The shorter ratios, I was wrong about. They would mean nothing in your case, since you're driving on a 1:1 ratio from front to rear output shafts.

In most cases, 4Lo is not recommended for use on any surface that isn't soft. As such, you shouldn't be outside of low gear when using it.

These really shouldn't have to be discussed... talk to a few offroaders that have had to limp home on FWD only, and you'll figure out that they're practices that should be adhered to fairly well.

The speed limitations for 4wd mode don't apply if you're using the motor in place of the front axle connection, because you won't be turning all 4 tires under power, so you can disregard that part.

Mounting the motor inline with the rear driveshaft DOES NOT subject it to suspension abuse. I'm not sure where you came up with that...

Using that configuration would also allow you to remove the motor from the driveline by removing a few bolts and replacing the original drive shaft... not sure how hard you think that is, but if you find it difficult to R&R a driveshaft with a carrier bearing, you probably shouldn't even be thinking about this type of mod.

Mounting it from the front input of the xfer case does not give you a "gear reduction for low speed use." as you'll be driving the rear shaft at a 1:1 speed through the xfer case, no matter what gear you're in, unless you have two differential sizes in the front and rear axle, which is highly unlikely. If both axles have the same differential speed, you'll have the same 1:1 ratio in the t-case no matter what range you select, as this is the nature of 4wd... turn front and back so they match each other based on the engine's input...

Thanks for your opinions. I'd like to hear other peoples inputs as well.