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Transmissions and final drives


Walter_Sobchak

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On 6/15/2017 at 3:02 PM, Xoon said:

Felt like sharing this gem:
http://www.ffi.no/no/Rapporter/08-01220.pdf

 

A report on hybrid electric vehicles. 

 

A neat idea here is to use the hybrid electric system to power a ETC gun. This could solve the power issue, at the cost of no or reduced mobility during firing. 

 

Xoon,

 

Thank you very much for this PDF! It's extremely useful, thought provoking, informative, and the focused comprehensiveness in it's coverage of hybrid vehicles for military use without the extraneous stuff that doesn't apply.

(like self congratulatory smug preachiness, moral exceptionalism, and the other bullshit topics about hybrid anything attract)

 

As I'm reading it,  I am actually gaining clarity on stuff that resources like technology of tanks only managed to confuse and frustrate me about even further.

 

There are several people off this site I'd like to pass a copy of this to if you are OK with my doing so.

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22 hours ago, roguetechie said:

 

Xoon,

 

Thank you very much for this PDF! It's extremely useful, thought provoking, informative, and the focused comprehensiveness in it's coverage of hybrid vehicles for military use without the extraneous stuff that doesn't apply.

(like self congratulatory smug preachiness, moral exceptionalism, and the other bullshit topics about hybrid anything attract)

 

As I'm reading it,  I am actually gaining clarity on stuff that resources like technology of tanks only managed to confuse and frustrate me about even further.

 

There are several people off this site I'd like to pass a copy of this to if you are OK with my doing so.

Feel free to share it as much as you want, anything I find for that matter.  It's not mine anyways. 

 

Found it at Forsvarets forskningsinstitutt's site (Norwegian Military Science Institute).

 

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  • 5 months later...

I found this quite interesting, and I would like people to share their opinion on this:

 

 

In short, magnetic gearing. Zero contact between the two "gears" meaning "no friction", no need for lubricant, very reliable and claimed efficiency of 99% at high speeds and "much higher at lower speeds compared to conventional gearing. 

 

What this means is that you can have a final drive with almost no wear and a very long lifespan, if we do no count the bearings. It also has a side effect of slipping when the torque goes past the rated torque. This means that the drive would disengage instead of breaking itself. I think this works well with electric motors, considering their long lifespan, which often needs a gearbox to optimize the torque. 

 

The company realized this and apparently made a Psuedo-direct drive, integrating it into the motor and claim a much better torque density. I think this would be quite useful for AFVs to reduce the size of the engine bay. 

 

 

They also made a magnetic CVT:
imgsize.php?w=265&img=MAGSPLIT-on-TEST.J

imgsize.php?w=265&img=MAGSPLIT2-on-build
Should be self explanatory for anyone that knows what a CVT is. Claims to be 32% more efficient that a conventional gearbox.

 

The only disadvantages I can think of is higher price and needing to keep the magnets below their Curie point. 

 

 

 

And we have magnetic bearings too:
en-after47-1.jpg?ts=1355199050

 

Simply, they are like magnetic gears, only as bearings. They can support a theoretically infinite RPM, with no friction. They can operate in a vacuum and in very hostile environments. 

 

They come in two types, active and passive. Active bearings use sensors and electromagnets in a feedback loop does a "tug of war" to keep the object in the center. A passive system uses permanent magnets. 

Some include a backup bearing in case of a failure. Same disadvantages as above. 

 

 

This could make for a system with almost zero friction, no lubricant and a very long lifespan. In theory, non of these parts would ever need to be replaced, some maintenance would be needed to remove pill up of dirt and dust.

With a magnetic coupling, you could also have a sprocket that does need to compromise the armor, as it can transfer the power through it magnetically. 

 

Sources:
https://en.wikipedia.org/wiki/Magnetic_bearing

http://www.magnomatics.com/pages/technology/pseudo-direct-drive.htm

http://www.magnomatics.com/pages/technology/low-ratio-magnetic-gears.htm

http://www.magnomatics.com/pages/technology/magsplit.htm

http://www.magnomatics.com/

https://en.wikipedia.org/wiki/Magnetic_coupling

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Transferring power through the hull would screw with the efficiency - for conductive armour you'd induce eddy currents, and for non-conductive armour you'd still have a big "air" gap to deal with. Probably not worth it for AFV's, but if it eliminates the shaft seal then this could be very useful for submarines (depending on the EM signature)

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1 hour ago, Xlucine said:

Transferring power through the hull would screw with the efficiency - for conductive armour you'd induce eddy currents, and for non-conductive armour you'd still have a big "air" gap to deal with. Probably not worth it for AFV's, but if it eliminates the shaft seal then this could be very useful for submarines (depending on the EM signature)

Forgot that a big metal plate works as a conductor. 

 

Still, the air gap should not be too bad if something like ceramic are used. Alternatively, a composite sandwich of conductors and isolators could be used, like NERA.

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  • 3 months later...

Share some less-known information about cold war period tracked vehicle transmission

 

162347cuznu3p9wzlrwnp8.jpg

162308c85nc5kkrnng8l6i.jpg

Mithubishi transmission MT75 for STB, later known as Type 74.

The basic layout of MT75 is similar to the CD-500 transmission on M41 light tank, used by JGSDF in a short period after war.

But the Japanese tank designers prefer mechanical gearbox rather than hydramatic gearbox, they use a electro-mechanic high-low range instead of a torque converter. The high-low range part is described as "1次変速"(range first stage).

The steering mechanism is a single-radius, double differential type, operated by engaging steering clutch, also resemble the CD-500. 

 

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 

163000k592xi9pa958aoff.jpg

202358gvfmcnb7b3t944nt.png

 

Allison X-700 transmission, a 800-hp class transmission to replace XTG-411 on T95 medium tank in 1960s. 

Trials were successful but finally never adopted. The Army decided to develop a 1500-hp class transmission for XM803. 

X-700 then evolved into X-1100 transmission. The X-200 and X-300 were basically smaller variants of X-700. 

X-1100 users: M1 and its variants; Korean K9 "Thunder"; Turkish T-155 "Firtina"

X-300 users: Warrior IFV; CV90 series

X-200 users: M113 upgrade (A2 standard)

 

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

 

153258zeaxmpe9un9onzp8.jpg

124158c8cb8qzvm5q0mztv.jpg

Allison XHM-1500-B2, a hydrostatic-mechanical transmission developed in early 1970s. A competitor against X-1100 but less successful. 

Different parts were shown in different color. 

Orange: power input and forward-reverse shifting mechanism;

Blue: hydrostatic-mechanical speed range (mechanical planetary gears were not shown in cutaway);

Red: hydrostatic differential steering system; 

Green: output shaft and planetary gears. 

 

 

Hope you enjoy these pics. 

Edited by Monochromelody
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8 hours ago, Andrei_bt said:

Great ! Thanks! Looking info about Abrams diesel engine transmission.

 

Abrams diesel?  Do you mean diesel package proposed by General Dynamics a couple years ago?  With the MT 883 engine?  I'm not sure exactly what transmission they had the MT883 paired with, but I suspect it's something like this: http://www.allisontransmission.com/docs/default-source/specification-sheets/11119_atm_5250mx_sales_sheet.pdf?sfvrsn=2

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42 minutes ago, Andrei_bt said:

Thanks! Not only "diesel package proposed by General Dynamics a couple years ago"  also 70-s era competition.

Mostly train of gears of transmission.

The General Motors XM1 prototype used basically the same transmission as the Chrysler XM1, the Allison X1100.  The Gas turbine was coupled with the X1100-3B, the diesel AVCR-1360 was paired with the X1100-1A.

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Going through the stuff I pulled out of my father's house, I found a document on X1100 transmissions.  It's basically a paper copy of a powerpoint so it's a bit light on info, but I have scanned a few pages that had interesting data. There is a lot more, let me know if you want more scans of details.

 

x1100-1.jpg?w=680

x1100-2.jpg?w=680

x1100-3.jpg?w=680

 

x1100-4.jpg?w=680

 

x1100-5.jpg?w=680

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  • 3 months later...
  • 2 months later...

I have a curious question:

65S8RdZ.png

 

Lets say I have a car and I want to power it with hydraulics.

A engine is connected to a hydraulic pump via a torque converter. The hydraulic pump powers two motors that are plumbed in parallel. Would this work like a differential, or would a actual differential be needed? 

 

 

Also,

Could I use a pump/motor setup as a reduction gear? 

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3 hours ago, Xoon said:

I have a curious question:

65S8RdZ.png

 

Lets say I have a car and I want to power it with hydraulics.

A engine is connected to a hydraulic pump via a torque converter. The hydraulic pump powers two motors that are plumbed in parallel. Would this work like a differential, or would a actual differential be needed? 

 

 

Also,

Could I use a pump/motor setup as a reduction gear? 

You need a differential valve.  Here's a diagram of a simple platform lift with wheel mounted hydrostat motors and a differential valve system.

TuEqyOs.png

 

As to using a pump/motor for gearing, the answer is "maybe".

There are swashplate pumps and motors, but they are very expensive and tend to be much larger than an equivalent gear or vane type pump/motor.

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10 hours ago, Meplat said:

You need a differential valve.  Here's a diagram of a simple platform lift with wheel mounted hydrostat motors and a differential valve system.

TuEqyOs.png

 

As to using a pump/motor for gearing, the answer is "maybe".

There are swashplate pumps and motors, but they are very expensive and tend to be much larger than an equivalent gear or vane type pump/motor.

Thanks, I sadly do not have a lot of practical experience with hydraulics, so this was very helpful. 

 

I had a idea about a sort of hydraulic transmission. 

The idea was to use hydraulics instead of a mechanical reduction gear and differential, and then couple a accumulator to the system to absorb breaking power for later use. 

I have heard that hydraulic regenerative breaking has a efficiency of 90% compared to the  electrical at around 60%.  I also wonder if it is possible to completely lock the motors (assuming they are completely sealed, no run off), and use them as a low speed break/parking break. 

 

I wonder if a sort of insane diesel-electric-hydraulic parallel-series hybrid would be more efficient than a diesel-hybrid or conventional mechanical layout. 

 

I know that diesels are the most thermally efficient ICE. But a vehicle usually needs a generator and starter to power the vehicles electronics and easily start the ICE. So a motor/generator setup could be used. And since diesel need a turbocharger to make any meaningful power, a variable geometry turbocharger with a motor/generator setup could be used. A exhaust heat recovery system could also be used.   This effectively makes a soft hybrid. 

 

However, even with a purely electric vehicle, a electric motor still needs a reduction gear to get the best efficiency. So I thought, what if we couple this system to a hydraulic transmission?  
As far as I understand hydraulics, it is still kinetic energy, so it is a alternative to a mechanical system. With this we could integrate accumulators and get more efficient regenerative breaking, and locking the hydraulic motors to hold the vehicle still. 

 

So when the vehicle starts its ICE with the motor/generator, which also powers the electrical system. To quickly accelerate it uses the motor/generator on the axle and the turbocharger to get instant acceleration and close to no turbo-lag. When cruising it uses the ICE, with assists from the electric and hydraulic system. When the vehicle breaks, the hydraulic system absorbs the energy and stores it in the accumulators, if more power is needed, the electric motor kicks in, and then the engine break. To hold the vehicle still, the hydraulic motors are locked. If the vehicle needs more power, the energy from the accumulators are transferred to the motor/generator to charge the battery. 

 

I might see if a can draw up a proper diagram if anyone is interested. 

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17 hours ago, Xoon said:

Lets say I have a car and I want to power it with hydraulics.

A engine is connected to a hydraulic pump via a torque converter.

 

Well, you dont really want to power a car with hydromotors. They do not really like continuous high speed operation, you will face overheating problems. Im a heavy equipment operator, so I have some experience with it.There was a job where the work site was about 6-7 kilometers away from where we parked the machines, its a lot for something that has a max top speed of 20km/h. No trailers were available, so we had to drive to the site every day. When we arrived, the hydromotors were searing hot, and had to let them cool down. Hydraulic oil change was also necessary much earlier than the specified time interval. 

But lets say you build a car with hydrostatic drive train. First, you do not need torque converter at all. Just connect the main pump directly to the engine. Then, you do not need two separate hydromotors. Just one, and connect it to the axles with a differential. As far as I know, all hydrostatic-driven, non skid-steer wheel loaders are constructed like this.

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21 minutes ago, heretic88 said:

 

Well, you dont really want to power a car with hydromotors. They do not really like continuous high speed operation, you will face overheating problems. Im a heavy equipment operator, so I have some experience with it.There was a job where the work site was about 6-7 kilometers away from where we parked the machines, its a lot for something that has a max top speed of 20km/h. No trailers were available, so we had to drive to the site every day. When we arrived, the hydromotors were searing hot, and had to let them cool down. Hydraulic oil change was also necessary much earlier than the specified time interval. 

But lets say you build a car with hydrostatic drive train. First, you do not need torque converter at all. Just connect the main pump directly to the engine. Then, you do not need two separate hydromotors. Just one, and connect it to the axles with a differential. As far as I know, all hydrostatic-driven, non skid-steer wheel loaders are constructed like this.

The idea of the thought experiment was to not use conventional mechanical parts. So a differential would be cheating. 

You have a good point about the torque converter, it is pretty much dead weight. I guess the pump could have a stall speed higher than the idle rpm. 

 

Though I think heavy equipment is fundamentally different from, say a car. Since they require much higher reliability, roughness and lower cost. As far as I have seen, most hydraulic driven heavy equipment use air cooled hydraulic motors. This would be a no go for a car. A liquid cooled motor would probably deal with the overheating issue. Does your vehicle have a duty cycle? 

 

I really appreciate that you share your experience, could you tell me some more? 

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8 hours ago, Xoon said:

Thanks, I sadly do not have a lot of practical experience with hydraulics, so this was very helpful. 

 

I had a idea about a sort of hydraulic transmission. 

The idea was to use hydraulics instead of a mechanical reduction gear and differential, and then couple a accumulator to the system to absorb breaking power for later use. 

I have heard that hydraulic regenerative breaking has a efficiency of 90% compared to the  electrical at around 60%.  I also wonder if it is possible to completely lock the motors (assuming they are completely sealed, no run off), and use them as a low speed break/parking break. 

 

I wonder if a sort of insane diesel-electric-hydraulic parallel-series hybrid would be more efficient than a diesel-hybrid or conventional mechanical layout. 

 

I know that diesels are the most thermally efficient ICE. But a vehicle usually needs a generator and starter to power the vehicles electronics and easily start the ICE. So a motor/generator setup could be used. And since diesel need a turbocharger to make any meaningful power, a variable geometry turbocharger with a motor/generator setup could be used. A exhaust heat recovery system could also be used.   This effectively makes a soft hybrid. 

 

However, even with a purely electric vehicle, a electric motor still needs a reduction gear to get the best efficiency. So I thought, what if we couple this system to a hydraulic transmission?  
As far as I understand hydraulics, it is still kinetic energy, so it is a alternative to a mechanical system. With this we could integrate accumulators and get more efficient regenerative breaking, and locking the hydraulic motors to hold the vehicle still. 

 

So when the vehicle starts its ICE with the motor/generator, which also powers the electrical system. To quickly accelerate it uses the motor/generator on the axle and the turbocharger to get instant acceleration and close to no turbo-lag. When cruising it uses the ICE, with assists from the electric and hydraulic system. When the vehicle breaks, the hydraulic system absorbs the energy and stores it in the accumulators, if more power is needed, the electric motor kicks in, and then the engine break. To hold the vehicle still, the hydraulic motors are locked. If the vehicle needs more power, the energy from the accumulators are transferred to the motor/generator to charge the battery. 

 

I might see if a can draw up a proper diagram if anyone is interested. 

Using an accumulator is almost a necessity in a hydrostat drive, simply to keep the thing from throwing you through the glass (or over the edge of a lift basket) when you stop moving. Without some kind of accumulator (or cushion cylinder) if you let off the drive, it would lock the wheels immediately (instead of slowing a bit before stopping).

 

If you hit the E-stop on say, a big JLG/Grove or Genie boom lift while cooking about at high speed, it WILL come to damn near a dead stop, immediately.

If you just let go of the travel stick, it will "soft stop", effected by the cushion cylinder in the drive system (an accumulator of sorts.).

 

You can use hydrostatic pressure to lock/set brakes (Called a line lock, you can install them on almost anything with hydraulic brakes) but most use a spring loaded brake (either drum, disc or pin and pawl) that requires the application of hydraulic pressure to release the brake.

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2 hours ago, Meplat said:

Using an accumulator is almost a necessity in a hydrostat drive, simply to keep the thing from throwing you through the glass (or over the edge of a lift basket) when you stop moving. Without some kind of accumulator (or cushion cylinder) if you let off the drive, it would lock the wheels immediately (instead of slowing a bit before stopping).

Why not let the motor freewheel? Simply stop powering the pump and the hydraulic liquid will flow through the system until it expends the energy and stops. Alternatively, you could "short circuit" the motors, by directing the hydraulic fluid from the outlet port to the inlet port. 

Variable breaking power could be accomplished with a throttle valve at the outlet port and/or feeding into a accumulator. 

If a constant pressure has to be provided, then this valve works like the throttle. 
Rotating direction can easily be  changed by a cross (?) valve. Not sure what it translates into. 

 

2 hours ago, Meplat said:

If you hit the E-stop on say, a big JLG/Grove or Genie boom lift while cooking about at high speed, it WILL come to damn near a dead stop, immediately.

If you just let go of the travel stick, it will "soft stop", effected by the cushion cylinder in the drive system (an accumulator of sorts.).

The E-stop sounds painful. 

 

2 hours ago, Meplat said:

You can use hydrostatic pressure to lock/set brakes (Called a line lock, you can install them on almost anything with hydraulic brakes) but most use a spring loaded brake (either drum, disc or pin and pawl) that requires the application of hydraulic pressure to release the brake.

I have been trying to find a breaking method that does not require friction breaks, and can lock the wheels without using power. I think line lock would have a better service life than conventional mechanical brakes, since it does not grind away, like a friction break. I guess a locking pin would be used for parking break. 

 

A simple safety feature would be a spring-loaded valve, which is normally closed, and powered by the hydraulic pressure from the system. If hydraulic pressure drops below critical levels, the breaks engage.  A second throttle valve would control breaking. 

 

For regenerative breaking, the flow would be directed into a high pressure accumulator, and out of a low pressure accumulator.  A relief valve would redirect the flow once the accumulators reach a certain pressure. This pressure would then be redirected thought the pump, which would drive the generator, charging the battery. Once the battery is full, the generator makes close to zero resistance, and the flow would circulate in the system, being restricted by the throttle valve until it grinds to close to a stop, then the throttle valve closes completely, locking the line. Then the parking break would be engaged, letting go of a spring, locking the driveline with a bolt, and releasing the safety valve. 

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3 hours ago, Xoon said:

Why not let the motor freewheel? Simply stop powering the pump and the hydraulic liquid will flow through the system until it expends the energy and stops. Alternatively, you could "short circuit" the motors, by directing the hydraulic fluid from the outlet port to the inlet port. 

Variable breaking power could be accomplished with a throttle valve at the outlet port and/or feeding into a accumulator. 

If a constant pressure has to be provided, then this valve works like the throttle. 
Rotating direction can easily be  changed by a cross (?) valve. Not sure what it translates into. 

Because closing a valve is pretty abrupt, and the fluid will not compress. (that is what the cushion cylinder is for)  You also do not want freewheeling when you are 100+ feet in the air trying to manuver around say, stadium lights.

You are not controlling the valves from the basket, you are using electricity to drive solenoids. You can get some "throttling" but once the valve shuts, there is no freewheeling.

 

 

3 hours ago, Xoon said:

 

The E-stop sounds painful. 

 

I have been trying to find a breaking method that does not require friction breaks, and can lock the wheels without using power. I think line lock would have a better service life than conventional mechanical brakes, since it does not grind away, like a friction break. I guess a locking pin would be used for parking break. 

It still causes wear, just to a different component. In this case, the fluid itself, and the motors.  (and the tires).

3 hours ago, Xoon said:

 

A simple safety feature would be a spring-loaded valve, which is normally closed, and powered by the hydraulic pressure from the system. If hydraulic pressure drops below critical levels, the breaks engage.  A second throttle valve would control breaking. 

That is how most brakes work on the stuff I deal with. No pressure = locked brakes.  There are even systems to allow you to move them, if the drives are dead, via a hand pump and locking valve, to "lock" the brake stack or pin-cylinder open.

3 hours ago, Xoon said:

 

For regenerative breaking, the flow would be directed into a high pressure accumulator, and out of a low pressure accumulator.  A relief valve would redirect the flow once the accumulators reach a certain pressure. This pressure would then be redirected thought the pump, which would drive the generator, charging the battery. Once the battery is full, the generator makes close to zero resistance, and the flow would circulate in the system, being restricted by the throttle valve until it grinds to close to a stop, then the throttle valve closes completely, locking the line. Then the parking break would be engaged, letting go of a spring, locking the driveline with a bolt, and releasing the safety valve. 

The sole issue here is having an accumulator big enough to make it work as more than a surge supressor.

You need a BIG tank to make this worthwhile.

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8 hours ago, Meplat said:

Because closing a valve is pretty abrupt, and the fluid will not compress. (that is what the cushion cylinder is for)  You also do not want freewheeling when you are 100+ feet in the air trying to manuver around say, stadium lights.

You are not controlling the valves from the basket, you are using electricity to drive solenoids. You can get some "throttling" but once the valve shuts, there is no freewheeling.

I see. 

 

8 hours ago, Meplat said:

It still causes wear, just to a different component. In this case, the fluid itself, and the motors.  (and the tires).

I wonder if it would be more cost effective. 

 

8 hours ago, Meplat said:

That is how most brakes work on the stuff I deal with. No pressure = locked brakes.  There are even systems to allow you to move them, if the drives are dead, via a hand pump and locking valve, to "lock" the brake stack or pin-cylinder open.

Unlocking the breaks for towing would be useful. 

Forgot about that one.

 

8 hours ago, Meplat said:

The sole issue here is having an accumulator big enough to make it work as more than a surge supressor.

You need a BIG tank to make this worthwhile.

True. I think it only would need to be big enough to capture one or two full breaking sessions from top speed. 

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15 hours ago, Xoon said:

I have been trying to find a breaking method that does not require friction breaks, and can lock the wheels without using power. I think line lock would have a better service life than conventional mechanical brakes, since it does not grind away, like a friction break. I guess a locking pin would be used for parking break. 

 

On hydrostatic driven wheel loader you have 2 methods of braking. First, is simply let your foot off from the accelerator pedal. The pressure in the system acts on the pump, slowing down the machine. Most of the time you use this method. But sometimes, this is not enough, for example emergency braking, or simply holding the machine when pushing up material to the pile. This is why you have a conventional brake too, on my machine it is located on the drive shaft that powers the front axle, it is a simple disc brake. It is also used as a parking brake.

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