What is this

woodlandfarms · Jan 11, 2008

My 1850 is a Hydraulic brake... I have to flip a lever and let the system pressurize before I can roll it forward or reverse. If you need to move the PT and cannot start it you must hand pump the brake, then release the brake lever (also you must lossens some nut on the pump or direction control at the pump so the oil can flow free).

Flipping the lever kills the hydraulic juice to the wheels (treadle goes inactive).

Now, I am not sure if the treadle is dead but when you apply pressure there is no bogging of the system (I would think it would bog if the treadle remained pressurized).

Anyway... There may be springs in the brakes. I am not sure how the brakes actually work on the PT 1850.

J_J · Jan 11, 2008

woodlandfarms said:
My 1850 is a Hydraulic brake... I have to flip a lever and let the system pressurize before I can roll it forward or reverse. If you need to move the PT and cannot start it you must hand pump the brake, then release the brake lever (also you must lossens some nut on the pump or direction control at the pump so the oil can flow free).

Flipping the lever kills the hydraulic juice to the wheels (treadle goes inactive).

Now, I am not sure if the treadle is dead but when you apply pressure there is no bogging of the system (I would think it would bog if the treadle remained pressurized).

Anyway... There may be springs in the brakes. I am not sure how the brakes actually work on the PT 1850.

Carl,

What you are doing by flipping the lever, is to open a small orifice in the pump to let fluid free flow through the wheel motors and pump. Since the orifice is very small, you should only tow a short distance, or the hydraulic fluid will heat up really fast.
The fluid is actually bypassing the pistons in the pump. The engine should not be running.

Based on what you have said, I believe that your wheel motors are spring activated, and when you are pumping it up, the hydraulic pressure that you just pumped into the accumulator is then used to release the brakes. It would only be logical.

My old 1445 uses a spring loaded pin to engage a notch is a disk , and that is only for a parking brake. I could have used a braking system when my 1445 was rolling backward down a hill with no control.

ponytug · Jan 11, 2008

J.J.

Your understanding is my understanding.
Sorry to have been unclear. The brakes in the 1445 are spring on, with hydraulic overpressure to release them. There is a parking brake, which electrically opens a solenoid to dump the pressure and apply the brakes.

The spring applied brakes with hydraulic overpressure are available on a number of wheel motors from several manufacturers. To my knowledge, they are only used on the 1445, 1460, 1845, and the 1850. It was a major reason why I didn't buy the 1430.

I hope I never have to go through this procedure, because it would mean that I have a very, very sick PT:

To move my generation 1445 without engine power,

You have to remove the brake pressure output plug on the brake interlock manifold.
Then connect a hydraulic hand pump and a pressure guage, both user supplied.
Then loosen the tow valve 1- 1.5 turns, turn the ignition key to on, and turn the parking brake to off.
Then pump up the system to 600psi to release the brakes, but you probably want to chock the unit so it doesn't roll as you get to pressure.
You turn the ignition key to off or the parking brake switch to on to stop. (Whereupon you would need to pump up the brakes again, if you wanted to move it farther.)

The 18XX series have the hand pump built in as part of the brake tender. If it were a common need, I would add the pump, and a valved, and plumb the pump in permanently.

All the best,
Peter

J_J said:
Peter,
Are your brakes spring applied or hydraulic applied? I remember reading somewhere, that the brakes were spring loaded, and when stopped the spring applied brakes would keep the hydraulic motor from turning. When there was enough pressure built up in the fwd or reverse mode, part of the hydraulic fluid going to the motor pushes the springs back allowing the motor to turn. I can't remember if this system was used on hydraulic motors from PT, or other manufactures.

Although hydraulic accumulators are used to dampen out pulsations, in some system, I am thinking that the accumulators used on the PT is used for the brake system. Is it true that you can pump up the brakes on certain PT's? If this is true then the hydraulic accumulator is used to store fluid under pressure for the brake system.

If you have the spring applied brakes, and you have to move the PT with engine off, what do you do, pump up the system to get the brakes to release, and of course turn the the free flow valve on the tram?

ponytug · Jan 11, 2008

I remember reading this in another post of yours. Your story put the fear of God in me about this sort of accident, which is why I went for the 1445. We have lots of 25-30 degree slopes.

All the best,

Peter

J_J said:
...My old 1445 uses a spring loaded pin to engage a notch is a disk , and that is only for a parking brake. I could have used a braking system when my 1445 was rolling backward down a hill with no control.

J_J · Jan 11, 2008

ponytug said:
J.J.

Your understanding is my understanding.
Sorry to have been unclear. The brakes in the 1445 are spring on, with hydraulic overpressure to release them. There is a parking brake, which electrically opens a solenoid to dump the pressure and apply the brakes.

The spring applied brakes with hydraulic overpressure are available on a number of wheel motors from several manufacturers. To my knowledge, they are only used on the 1445, 1460, 1845, and the 1850. It was a major reason why I didn't buy the 1430.

I hope I never have to go through this procedure, because it would mean that I have a very, very sick PT:

To move my generation 1445 without engine power,

you have to remove the brake pressure output plug on the brake interlock manifold.

Then connect a hydraulic hand pump with pressure guage, both user supplied.

Then loosen the tow valve 1- 1.5 turns, turn the ignition key to on, and turn the parking brake to off.

Then pump up the system to 600psi to release the brakes, but you probably want to chock the unit so it doesn't roll as you get to pressure.

You turn the ignition key to off or the parking brake switch to on to stop. (Whereupon you would need to pump up the brakes again, if you wanted to move it farther.)

Peter,

That was a good explanation. Thanks.

Do you happen to have a hydraulic schematic for your 1445 you could send me?

ponytug · Jan 11, 2008

Your welcome! I'm always glad to help.

Hydraulic manual:
Boy, I wish I had one. After opening my PT manual, and not finding any schematics, I queried Terry about a hydraulic schematic and an electrical schematic. Both were said to be being rewritten...not that I could get an old one...

All the best,

Peter

J_J said:
That was a good explanation. Thanks.

Do you happen to have a hydraulic schematic for your 1445 you could send me?

Bob999 · Jan 11, 2008

It is my understanding that the brake system on the slope mowers--the 1845 and 1850 is somewhat different than the system on the 1445 and 1460.

I can be quite definite about the 1845 because I have one. The brakes are NOT integral the the wheel motors--they are external and independent of the operation of the wheel motors. (The brake disks are of course mounted on the axle which comes from the motor). The brake is spring applied. The brake is released by hydraulic pressure which can come either from an hydraulic sytem that is powered by the engine or from hydraulic pressure created by a hand pump--the brake tender. A lever on the brake tender controls the application of hydraulic pressure from the engine powered system. The level is automatically moved to release hydraulic pressure if the engine stops or if hydraulic pressure in the engine powered system goes to zero. Thus there is an automatic safety system that applies the brakes if hydraulic pressure is lost--because the engine stops or a hose bursts.

My understanding--I don't know from personal experience--is that the brake system on the 1445 and 1460 is NOT automatically applied in the event hydraulic pressure is lost. Rather my understanding is that it must be manually activiated. Please correct me if I am wrong.

Rip · Jan 12, 2008

Bob, your understanding of the BrakeTender system as used on the 18** series (and PowerTrac's mining tractors as well) is correct. They are both in essence a "Fail-Safe Spring Apply/Pressure Release"-type system that use heavy springs to apply the brake, and hydraulic pressure to release it.

The 18** series machines use external calipers and discs where the other Red machines (except the 1430) have internal brake componants within the wheel motors. These are commonly used in other mobile hydraulicly driven machinery. These will apply full braking when hyd pressure drops below a set point, but will automatically release when pressure rises above that point. The non-BrakeTender equipped machines have a dash toggle to cut pressure to the brake system independent of the drive system to allow them to "apply" and serve as a parking or emergency brake.

In addition to the larger external brake componants, the BrakeTender can be manually pumped up to release the brakes if a disabled tractor needs to be moved. It also has to have the handle manually moved by the operator if automatically "set" by low pressure (does not have to go to zero) such as if you bog the engine down too much.

Both systems are either "Full On" or "Full Off" in that they can not be modulated as an operating brake. Unlike a "pin" system, however, they can be applied with the machine in motion without damaging anything, although the stop may be fairly abrupt. Neither of these systems will jam or bind-up if the machine is parked on a slope or otherwise under load.

J_J · Jan 12, 2008

I found this on the Internet about brake tender. Check it out and see if any of this applies to the PT's.

singlehand

Check out the data at the bottom of the page. Some good schematics, and pictures.

This is their mailing address.

Mail: P.O. Box 539 Tazewell Industrial Park, Tazewell, VA 24651 Three guesses who else operates from there.

Bob999 · Jan 12, 2008

J_J said:
I found this on the Internet about brake tender. Check it out and see if any of this applies to the PT's.

singlehand

Check out the data at the bottom of the page. Some good schematics, and pictures.

This is their mailing address.

Mail: P.O. Box 539 Tazewell Industrial Park, Tazewell, VA 24651 Three guesses who else operates from there.

The parent of Power Trac started out making mining equipment. My understanding is that the brake tender system is a safety system required to meet mining machine saftey regulations.