[Electric Car-Nut]

Parking brake as part of motor/transmission adaptor
Hello? It just hit me, hey you, designer, feel free to be inspired. Almost every one of the EV conversions includes a adapter plate and spacer between the motor and transmission some with a clutch and some not. If you use a clutch leave the flywheel complete, and in the starter opening put a cable operated "PAW" to engage the starter ring gear teeth. If you aren’t using a clutch just a coupling make an enlarged flange on the adapter and bolt a brake disk rotor or a brake drum or a "V" pulley to it and then mount shoes on the adapter plate or a caliper or a band actuator to fit in the pulley and you can make a wonderful
"Parking Brake” (It only needs to be a small one because the gearing multiplies its effectiveness. Use a standard assembly from a rear wheel brake assembly or a off-road vehicle,(ATV) so parts will be available in the future for service.
Regards,
Dennis

 

[Guest]

What's wrong with using the standard parking brakes? They use the brakes already on the car. It's not like putting an automatic in park. No real need for the extra complications of another modification. Just be sure your parking brakes work and your good to go. Now if you want to lock the transmission then you'd need a tranny lock. I think that is what your after and I like the pawl lock for the starter ring. Nice thinking.

Pete

 

[DavidDymaxion]

In freezing weather the parking brake can freeze stuck. Also, some cars take a very strong arm to get enough force to hold them on a steep hill.

Another way to create a "park" position is to put the car into reverse and a forward gear at the same time. You'd probably have to custom make a separate lever for reverse for this to work.

What's wrong with using the standard parking brakes? They use the brakes already on the car. It's not like putting an automatic in park. No real need for the extra complications of another modification. Just be sure your parking brakes work and your good to go. Now if you want to lock the transmission then you'd need a tranny lock. I think that is what your after and I like the pawl lock for the starter ring. Nice thinking.

Pete

 

[toddshotrods]

I'm keeping the forklift parking brake (on the CE shaft) on my race rod. It's very discreet, and makes for a cleaner show vehicle with no e-brake cables running to the rear end. With the forced-air cooling pulley over the brake drum, no one will even realize it's there.

 

[maxvtol]

I will probably come up with some sort of verbal warning system to make sure my emergency brake is engaged when parked since I live on a rather steep hill. I kind of like the parking pawl / starter gear tooth idea if you could have the starter tooth brake engage when the ignition switch is shut off. But I don't know how you could make it fail safely.

 

[Thaniel]

I've thought of taking the parking mechanism off a auto trans and fitting it to the rear of my trans or motor or something. Whatever design someone chooses I would want to ensure it can't engage while the shaft is spinning. I believe auto trans are designed this way. Well at least my truck is designed that way as I shoved it into park once while still coasting and it just clicked until it stopped.

The down side to fitting the unit to the motor is if the car is inadvertantly left out of gear it won't do any good. The upside to having one is not all parking brakes work all that well and a parking Pawl on the motor or trans would add piece of mind. I have a flywheel on mine so yes it does get my mind thinking.

 

[Wirecutter]

The way park is most often implemented is with a pin that is dropped into a hole in a shaft inside the transmission. Perhaps the output shaft. The rest of the trans is in the same configuration as neutral. If the vehicle is in motion when you slam it into park, it doesn't grind up all your gears, the pin just won't drop into the hole. The clicking that results is the hole passing the pin and the pin perhaps boogering up the opening to the hole a bit. When the vehicle slows down enough for the pin to be able to drop into the hole, it does and the vehicle stops with a little jerk.

--M

 

[Coley]

Most automatic transmissions use a locking pawl that engages the planetary gear set. There is a gear made just for the pawl, on that gear set.
There is NO "hole" for a pin to go into.

 

[piotrsko]

many of the older commercial trucks use a driveshaft brake which is just a band around the 'shaft that shrinks when you apply the brake lever. I'm thinking that one could be had for about $10 US.

 

[Electric Car-Nut]

piotrsko, that is what I was trying to encourage. In areas where we see snow in the winter smart drivers don,t use the parking brake because they often freeze together.
We used to put the car in first so it didn't drift away. or freeze. with an electric conversion on a stick shift that cannot be done so adding a brake band to the drive shaft sounds like a GREAT accessory. Why don't you price new / replacement units and sell them to other EV ers on the web perhaps...

 

[Woodsmith]

I do like the idea of a locking transmission pawl but that is from my time messing with Land Rovers and winches. A locked transmission was always a bit more reassuring then a worn out transmission drum brake.

It needs to be well indicated though, I wouldn't like my MOT tester yanking on the tranmission locking pawl when he is doing a brake test.

 

[Electric Car-Nut]

I do agree with you a "Transmission LOCK" is not an emergency brake. It is a simpler solution mechanically. I prefer a band around a pulley or two shoes inside a small drum, or a cable operated caliper on a small disk all on the motor shaft to transmission input shaft coupling with the band, or brake shoes or caliper mounted to the motor to transmission bell housing adapter plate, and they are all true "emergency" brakes also.

 

[Coley]

I park my EV with the emergency brake all year round and have not had a brake freeze.

One of the reasons for this is because the brake drum gets warm when driving and evaporates water off, as it cools.

Even temps down to 10 below O, have not been a problem.

Used to have a line lock on an old truck that locked all 4 wheels and never had it freeze them either. Single master cyl-drum brakes.

 

[ngrimm]

I'm wondering if the parking brake will be enough to hold my 71 Toyota pickup once the conversion is complete. In fact the first time I pulled it the cable broke. It's just that there is nothing to fall back on when it fails. That's why I agree with the OP that it would be nice to also have a cable operated brake on the motor coupler etc. I think freezing of the parking brake may also be caused by water in the cable housings in the old cars due to missing rubber boots. Another problem with parking brakes with drums is that they don't hold as well going backwards as they do forward.

 

[Woodsmith]

Another problem with parking brakes with drums is that they don't hold as well going backwards as they do forward.

That depends on the type of drum brake arrangement.

Usually the front brakes are twin leading shoe which only work well going forward.
The parking/emergency brake usually works on the rear brakes which are leading and trailing shoes and so should work with equal ineffectiveness in both directions.
Or at least that is what it is like in the UK.

 

[Woodsmith]

I park my EV with the emergency brake all year round and have not had a brake freeze.

One of the reasons for this is because the brake drum gets warm when driving and evaporates water off, as it cools.

Even temps down to 10 below O, have not been a problem.

Used to have a line lock on an old truck that locked all 4 wheels and never had it freeze them either. Single master cyl-drum brakes.

Brakes often 'freeze' because the cables are frozen more so then the brake itself. However, sometimes when a car has been left standing for some time, maybe put away fro the winter, condensation will form in the drum and rust will cause the brake shoes to stick to the drum.

 

[ngrimm]

That depends on the type of drum brake arrangement.

Usually the front brakes are twin leading shoe which only work well going forward.
The parking/emergency brake usually works on the rear brakes which are leading and trailing shoes and so should work with equal ineffectiveness in both directions.
Or at least that is what it is like in the UK.

I don't think I have ever seen a car in the US that had both shoes the same length on the same drum. I have been able to easily back out of a parking spot many times after forgetting to release the parking brake but was reminded when the car wouldn't move forward. Of course I've also tried to put my daughter's Land Rover in gear and turned the windshield washers on instead.

 

[Woodsmith]

I don't think I have ever seen a car in the US that had both shoes the same length on the same drum.

Twin leading shoe on a front drum brake - two cylinders and when activated both shoes will try to 'wrap' with the rotating drum increasing brake effectiveness but only in one direction.

Single leading shoe on a rear drum brake - single double acting cylinder usually with the parking brake lever included. When activated one shoe will 'wrap' with the drum in the forward direction the other is less effective. However, it should provide a similar level of effectiveness in both dirctions when used as a parking brake.

 

[ngrimm]

I think the key word is "should". The parking brake is still only spreading the shoes from one side so I assume it is wrapping in the way they described. Either I just happened to get nothing but defective cars that roll backward easier than forward in the 40 years I have been driving or I'm just plain stupid and couldn't possibly know the difference.

 

[Woodsmith]

I don't think the parking brake was up to much in older cars anyway. I grew up never wanting to relying on them.

It has only been my most recent new cars that would hold on the parking brake everytime. I think that is more down to a dedicated drum or caliper incorporated in a rear disc set up.