hydraulic negative brake control

[maxfluid]

Hi.

I would need a straight to control the negative hydraulic brake integrated into a translation gear.

currently the brake unlock is connected directly to the g output of a variable flow pump, which also connects the joystics for the forward/back.so as soon as I turn on the thermal motor the variable pump will gnare the aux load pressure and immediately unlock the negative brake of the motor.
I would like instead to unlock the brake only when with the joystic command ahead/back of the engine through the variable flow pump.
I would like to unlock the brake always with the low pressure of the output g of the pump but do not know how to do.what kind of circuit/valves can I use to implement this solution?
Thank you.

Hi.

 

[MBT]

Um...
but the question I ask myself is this:
Why do you use a variable pump?

in my modest opinion it would be more sympathetic to use a fixed flow pump and a proportional flow regulator valve to control the engine

above, connect the outputs to and b of your valve with x and y inputs of a valve or (flip-flop or shuttle valve). the exit at the shuttle valve will command your engine.

 

[Enigma]

Um...
but the question I ask myself is this:
Why do you use a variable pump?

in my modest opinion it would be more sympathetic to use a fixed flow pump and a proportional flow regulator valve to control the engine

above, connect the outputs to and b of your valve with x and y inputs of a valve or (flip-flop or shuttle valve). the exit at the shuttle valve will command your engine.

quoto...
The only thing I'd pay attention to is the minimum unblocking pressure of the "hydraulic brake". . .


enigma

 

[maxfluid]

In fact I have not been a clear bike, I try again and in case I make a scheme:


I have a small cyngolate (motocarriola) that mounts two pumps with variable flow in closed circuit that command two motors with negative brake for the translation. the servocomandi that move the inclination of the plates of the pumps with variable displacement (and therefore the velocity of rotation of the motors) are fed directmethn from the low pressure load pump taken from the pump at variable flow. the gear motor is then commanded by the sends a and b at the high pressure from the variable pump.
now we come to the unblocking of the negative brake of the driver:to shut down the brake needs a pressure of at least 15 bar. these 15 bars are taken from the oversupply circuit of the variable displaced pump (the same that serves to move the servocommands) that is calibrated to 20 bar.
so when I turn on the vehicle I immediately got the 20 bars and then the brake is unlocked even if I have not yet moved the servo controls to turn the engine.
if the vehicle is for example in slope with thermal motor on and then pressure of the servocommands the brake is unlocked and tends to move if at full load (only the reduction ratio of the gear motor makes from brake).
I would like to modify the brake unlocking circuit to make sure that the brake unblockcch only when drives the servo controls to rotate the engines.
I would like to find a solution for example by taking pressure from the servo controls themselves and with a valve operate, in conjunction with the movement of the servo control, the release of the brake.
What I would like to do is to find a valve that with a small control pressure (high from the servo control even just moved) let me get the 20 bar to the brake and as soon as the servo control returns in neutral position the brake pressure is removed.
Hi.

 

[MBT]

So, that's what I told you earlier.
use a shuttle valve connected to the outputs a and b of the servo control and whose output feeds the brake.
If the pressure out of the servovalve is too low, then you can do this:
a and b of the servovalvola enter x and y of the shuttle
the exit to the shuttle enters as x in a valve 3/2, whose feeding p comes from the high pressure pump (it goes obviously to exhaust) and whose to the brake
so happens that:
- when you move the servo command, in any direction, the shuttle valve hears it and from an exit to 3/2
- the 3/2 (which is activated with little pressure) is excited by the shuttle and sends high pressure oil to the brake, which is unlocked.
- when your servo control returns to zero (the crazy position), the shuttle power pressure will fall to zero (download through the engine)
- as a result, the piloting pressure of 3/2 goes to zero and the latter discharges the brake pressure, blocking it

mand

 

[Enigma]

:finger:

mand

enigma

p.s. @maxfluid: however for the next few times post a scheme... :smile:

 

[Enigma]

during lunch break I made the plumbing scheme...
View attachment Schema.pdfenigma

 

[maxfluid]

during lunch break I made the plumbing scheme...
View attachment 34811enigma

Thank you so much to all for the clear answer. Next time I'll post a pattern. Now I'm going to work!