Trielectric
Posts: 30
Joined: Fri Aug 10, 2012 9:15 am
Location: SE North Carolina

Re: Single Speed Transmission

Mon Sep 10, 2012 8:17 pm

As for the comment from dfw123 on neutral coasting...
I see no reason coasting in neutral would be damaging to the FFE. The transmission gears are turning any time the cars front wheels are turning. The spinning big gears lubricate the transmission by throwing the oil up on all the gears(& bearings). I am not sure if the bearings are sealed or lubricated by the splash. But the first gear has visible rollers in it in the parts diagram leading one to assume all the bearings are lubricated by the splash.
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In a front engine, rear drive, manual transmission car, pushing in the clutch(or shutting off the engine and putting the shifter in neutral allows the transmission counter shaft to stop, this stops the splash lubrication of the transmision, especially to the upper main shaft. Failed transmission is next, usually starting in the mainshaft to input shaft bearing. Automatic transmisons of the same setup need the engine running to provide the lubricating oil for the whole transmission. Coasting down a hill very fast with an automatic in neutral and engine idiling would not provide as much lubrication as was designed to all the disengaged but touching clutch plates because the pump is turning slowly with the engine. (Not fast as the drive shaft would be turning the engine faster). There are many spins on this issue and front engine, FWD cars are a different breed and have many more options for oiling or not. I see none of these problems with the FFE as long as it has oil in it. We have bought 2 new Mustang Cobras over the years. I found the transmission oil level extremely low in both cars when getting them home from the dealers(different dealers for both). I plan on checking the FFE soon. It is a pain getting to the plug.

Charged Up
Posts: 59
Joined: Wed Aug 10, 2011 7:13 pm
Location: Virginia

Re: Single Speed Transmission

Tue Sep 11, 2012 5:00 am

Trielectric wrote:Our "L" gear shift position must be electrical in the motor. The only reason for it to be there appears to be an ancient Federal law that you must have a way to slow down using the engine/motor turning resistance. This came about when brake failures were common place and automatics started to become popular.
For those who live in the hills or the mountains having an L option might be handy. Yes they could achieve the same regen with the brake pedal but this saves them from having to use that.

Many Volt owners use L exclusively because it allows them to basically drive one footed. They swear they are more efficient. And I swear there is absolutely no way they can be more efficient in L ;)

A position I feel somewhat vindicated on by this from p.264 of the 2012 owner's manual:
L (Low)
• Provides maximum motor braking.
• Is not intended for use under extended or normal driving conditions
and results in less miles per charge.
• The transmission may be shifted into L (Low) at any vehicle speed.

Trielectric
Posts: 30
Joined: Fri Aug 10, 2012 9:15 am
Location: SE North Carolina

Re: Single Speed Transmission

Fri Oct 19, 2012 7:59 pm

I checked my Ford Focus Electric transmission oil level today. It was right where it should be , just barely running out of the fill hole with the fill plug out. The fill & drain plugs require a Torx 55 driver to remove them. Ford has improved on filling their new cars with transmission oil. I did find 3 holes in the plastic undercar sheild that had no screws in them. The plastic nuts were there, but no screws. :?

Redfocus
Posts: 6
Joined: Sat Feb 02, 2013 3:57 pm

Re: Single Speed Transmission

Sat Feb 09, 2013 8:36 pm

Charged Up wrote:
mrpalerider wrote:I'm surprised their not putting transmissions in these things, they'd get better mileage/per charge if they added gearing to reduce the motor load at low speed.

Not necessarily. In general, electric motors are more efficient at higher RPMs. Yes you have full torque at 0 rpm, but the motor is least efficient at lower RPMs. As the torque falls off at higher RPMs the efficiency goes up.

Adding gears might give better acceleration at various speed bands, but would likely lower efficiency.
Not sure I understand your reply to mrpalerider. Having one more gear for highway speeds for example would allow the drain on the batteries to be less an extend the range of the car for example.

WattsUp
Posts: 2113
Joined: Mon Jan 07, 2013 2:58 am
Location: SF Bay Area, CA

Re: Single Speed Transmission

Sat Mar 16, 2013 2:27 am

@Redfocus:

Not all mechanical sensibilities from the ICE world apply in the EV world.

Adding a gear "for highway speeds" to an EV would mean the motor would run slower (when "in" that gear). Such gearing can make sense for an internal combustion engine (which is less efficient at higher RPMs), but not for an electric motor (which is more efficient at higher RPMs). Also, adding extra gears would only increase the overall friction in the system, actually slightly decreasing efficiency.

The best way to build an electric car is to choose an electric motor that is efficient over the range of RPMs required to drive the car at the required speeds. Hopefully, this is what Ford has done. (They would be pretty silly to have not.)
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Redfocus
Posts: 6
Joined: Sat Feb 02, 2013 3:57 pm

Re: Single Speed Transmission

Fri Apr 26, 2013 4:29 pm

Hi,

True the electric motor is more/most efficient at 60 to 90 % of maximum RPMs but the current range limitation is the battery charge. So while lowering the efficiency of the drive train and motor the drain on the battery would be less. Question is will the tradeoffs increase the range? I believe the rule of thumb for transmissions is an 18% loss so it is significant still I wonder....

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