Simba Freeflow fan conversion

[Romeogolf]

Afternoon all,

Whilst waiting for the spring, I have been looking into converting the fan on my 4m Freeflow from a pto pump to a spool connection. I already have a 3/4 return in the tractor for the sprayer, and wish to make use of that as a return. Has anyone else done this, and if so have you any pointers? In the attached picture I have ascertained that the pipes with a white cable tie should go together and complete into the return circuit. Presumably the pipe into the flow control valve on the machine is the feed and the one on the bottom of the tank is the return. I will be bypassing the machines tank altogether. Hope that makes some sort of sense....

 

[Mr Happy]

The pipe at the bottom of the hyd tank is the suction pipe that currently supplies hyd oil to the hyd pump. The hyd pipe at the bottom of the pressure relief valve (PRV) will need connecting to the the tractor, currently it will be connected to the outlet port of the hyd pump and the PRV . The three pipes that are connected to the return filter must be connected to a free flow port on the tractor.

 

[Bob lincs]

Take the two pipes off the motor , connect one to the flow from the tractor and the other to the free flow return . Regulate fan speed with your spool flow adjuster . Link both the pipes with a small pipe to prevent over Erving the motor (I think) Simple as that . Both of our drills are piped like this and we have no problems.

 

[Flat 10]

Why do you want to do this? So you don’t need full pto revs? Didn’t it used to be fairly common for people to mount engines on the drill as they were so hard to pull?

 

[Andrew]

Take everything off the drill apart from the fan motor.

There will be 3 pipes into the motor.
1) Inlet to the motor. Plug this into spool pressure.
2) Outlet from the motor. Plug this into spool return. These motors can be plumbed in series and can easily cope with 200bar back pressure, let alone the 20bar you get on a spool.
3) The next piece of plumbing is a one way valve connecting the pressure and return lines. This must be fitted so oil can go from the return line to the pressure line, NOT the other direction. This means oil will just loop through the motor when you stop the spool letting it run down, preventing damage. It also prevents the motor spinning backwards.
4) The third pipe from the motor is the case drain, some motors can only cope with 10bar back pressure and WILL BLOW UP if this is plugged into a spool, so THIS pipe needs to go into free flow return.

Problems: oil will get warmer as it's going back through the spool. If the case drain line becomes disconnected the motor will go bang.

THE (preferred) ALTERNATIVE

1) As before.
2) Plug into free flow return.
3) One way valve as before.
4) T the case drain line into the return line. Fit a flow restrictor in the case drain line of about 0.75mm size. A blocked male male fitting is best for this, then just drill the hole. NOTE - check with a proper specialist on the hole size.

If you follow this method, the oil will stay cooler as it's all going back through a free flow return. It's a bit more 'idiot proof' when plugging in.
However, from experience, on REALLY cold days (-15 in central Europe) it can blow the motor up. This is because oil is lazy. When all the oil is cold and thick, rather than start the oil in the return line moving, the oil goes back down the case drain line and makes the motor go bang. This is why the small restrictor is there, to iron out any pressure spikes. So it is critical to get the right sized hole.
It is unlikely to get that cold in Wiltshire, but every time on startup there will still be a small pressure spike that will cause the motor to fail eventually.

When you want to start the fan just pressurise the spool. It's good practise to slowly pull the lever to get the fan up to speed, to minimise the pressure spike I mentioned earlier. If you can't do this you can get soft start valves you can fit - there may even be one in your PTO system,

To stop put it in neutral. The one way valve fitted between the pressure and return will look after the motor. Put it in float if you want but there will be no flow.
Just vary the flow out of the spool to regulate motor speed.

When you first use the fan in the spools, I suggest slowly increasing the flow and monitoring the fan speed. I think it is a Crary fan on the Simba, most of these are rated to 6000rpm. If your tractor will make it spin more than about 5,500 rpm fit a flow restrictor hidden on the machine somewhere. Then if you forget to turn the flow down before using it, you won't blow the motor.

It's not as easy as you think. The motors are over £1000 so one mistake and it's expensive.

 

[Lincsman]

Why do you want to do this? So you don’t need full pto revs? Didn’t it used to be fairly common for people to mount engines on the drill as they were so hard to pull?

In my case, bearings went the the pump gearbox, was noisy anyway, and mounting it on the tractor a real pain, the tractor can maintain the correct flow regardless of engine RPM.
All I did was connect the tank bottom pipe to the TEE that is bolted to the tank top, so just bypassing the tank itself, and fit the pump connectors with quickfit ends, the return to a freeflow connection.

IMPORTANT! the tractor electronic spool is used in the "down" port (for constant pumping) and "float" to stop... NOT NEUTRAL... the motor cannot stop dead remember.

 

[Andrew]

IMPORTANT! the tractor electronic spool is used in the "down" port (for constant pumping) and "float" to stop... NOT NEUTRAL... the motor cannot stop dead remember.

If the motor has a one way bypass valve, then whether you have the spool in float or not, there will be no oil flow down the pipes.
I would recommend fitting this bypass to any motor, as some casual drivers may forget to put the spool in float. Also some tractors with electronic spools will only run in constant pumping in one direction, opposite to float. So it's impossible to do what you suggest.

 

[Lincsman]

If the motor has a one way bypass valve, then whether you have the spool in float or not, there will be no oil flow down the pipes.
I would recommend fitting this bypass to any motor, as some casual drivers may forget to put the spool in float. Also some tractors with electronic spools will only run in constant pumping in one direction, opposite to float. So it's impossible to do what you suggest.

Might be impossible but thats how mine has run for 5 years, I have also front mounted KRM tank with the same fan and it uses a "one way" valve for when the oils stops suddenly... it spins the same bit of oil round until it stops, not sure the freeflow drill has this valve?

 

[Romeogolf]

Thankyou for your replies. The reasons are numerous really.
Practically, the pump is heavy and awkward to fit, and on my tractor requires me to remove the pto guard which is a pain.

Operationally, the pto pump takes forever to get the fan up to speed, which if one is impatient as I have been at times, can lead to blocked pipes very quickly. It also requires the engine revs to remain constant. It would be far more pleasant to let the hyd pump worry about constant pump pressure allowing me to drive the tractor as I would rather.

Mechanically, the pto pump is leaking oil at quite a rate now, the last time drilling wheat it required constant topping up. I would rather not spend the money to repair it, instead get it converter to spool pump.

I wonder if these motors vary, as I only have two pipes into my motor. The pipe coming from the bottom of the tank will connect to the T piece that goes into the top of the tank with no altering. Doing this would allow anything from the PRV, the excess from the variation valve, and the return from the pump to go straight into the Freeflow return on the tractor. I assumed that would complete all the circuits required.
I have electric spools which can be set for constant pump down to 5% flow in either direction. I intended to start there and see how much of an increase was needed, and of course put it in float to let the motor spool down slowly. I don’t want to get this wrong!

 

[Lincsman]

Thankyou for your replies. The reasons are numerous really.
Practically, the pump is heavy and awkward to fit, and on my tractor requires me to remove the pto guard which is a pain.

Operationally, the pto pump takes forever to get the fan up to speed, which if one is impatient as I have been at times, can lead to blocked pipes very quickly. It also requires the engine revs to remain constant. It would be far more pleasant to let the hyd pump worry about constant pump pressure allowing me to drive the tractor as I would rather.

Mechanically, the pto pump is leaking oil at quite a rate now, the last time drilling wheat it required constant topping up. I would rather not spend the money to repair it, instead get it converter to spool pump.

I wonder if these motors vary, as I only have two pipes into my motor. The pipe coming from the bottom of the tank will connect to the T piece that goes into the top of the tank with no altering. Doing this would allow anything from the PRV, the excess from the variation valve, and the return from the pump to go straight into the Freeflow return on the tractor. I assumed that would complete all the circuits required.
I have electric spools which can be set for constant pump down to 5% flow in either direction. I intended to start there and see how much of an increase was needed, and of course put it in float to let the motor spool down slowly. I don’t want to get this wrong!

All I can say is I did what you plan IE connect the tank bottom pipe to the tank top pipe, and run it on electronic spools, the display will tell you how fast the fan is running, typically when cold it will start at 2500 rpm but after a few mins up the 4000 working speed. (All the fans i have seen are 2 pipes.)

 

[Andrew]

Might be impossible but thats how mine has run for 5 years, I have also front mounted KRM tank with the same fan and it uses a "one way" valve for when the oils stops suddenly... it spins the same bit of oil round until it stops, not sure the freeflow drill has this valve?

I only meant it's impossible for some tractors to run with the lever forwards in constant pumping as they simply can't - (eg new style Fastracs), not that your system was impossible. The valve your KRM tank is what I'm talking about - for the price of the few fittings I'd fit one to every motor, especially if converting it to spool driven.

 

[Lincsman]

I only meant it's impossible for some tractors to run with the lever forwards in constant pumping as they simply can't - (eg new style Fastracs), not that your system was impossible. The valve your KRM tank is what I'm talking about - for the price of the few fittings I'd fit one to every motor, especially if converting it to spool driven.

I see what you mean now, (good to know how advanced a new Fastrac is!) thinking about it you can stop a PTO at full rpm on its original set up, but maybe the fan can drive the pto until it stops? There are relief valves or flow control valves on the drill but no idea if these are for this issue?

 

[Romeogolf]

Struggling to get my head around this particular part of the equation... so forgive my ignorance... but if you did just put the spool in neutral, surely as long as the oil coming away from the motor is plumbed into a freeflow return I.e not through a controlled spool block, then the motor can just run itself down slowly anyway? I can see if it was coming back though the spool block and the spool was put into neutral then it would stop the flow and thus stop the motor dead, but wouldn’t a freeflow return prevent that?

 

[Lincsman]

Struggling to get my head around this particular part of the equation... so forgive my ignorance... but if you did just put the spool in neutral, surely as long as the oil coming away from the motor is plumbed into a freeflow return I.e not through a controlled spool block, then the motor can just run itself down slowly anyway? I can see if it was coming back though the spool block and the spool was put into neutral then it would stop the flow and thus stop the motor dead, but wouldn’t a freeflow return prevent that?

The fans are running at over 4000 rpm the motor would be trying to suck from a closed spool which I dont think would be good for it, obviously the freeflow return is way better than just off spools as my KRM front tank is. When i did my conversion I decided stopping on "float" would be best, the tractor has a locking device to stop you doing it wrong. (NH T8)

 

[cousinjack]

Afternoon all,

Whilst waiting for the spring, I have been looking into converting the fan on my 4m Freeflow from a pto pump to a spool connection. I already have a 3/4 return in the tractor for the sprayer, and wish to make use of that as a return. Has anyone else done this, and if so have you any pointers? In the attached picture I have ascertained that the pipes with a white cable tie should go together and complete into the return circuit. Presumably the pipe into the flow control valve on the machine is the feed and the one on the bottom of the tank is the return. I will be bypassing the machines tank altogether. Hope that makes some sort of sense....

What are you going to do with the old pto pump ??

I'm after one to convert my drill back to pto driven rather than the spool..

Because mine is a mounted drill, the tractor won't lift it at the end of the row unless the spool is turned off - oil takes the path of least resistance..

Let me know if you want to part with it ...

 

[Brisel]

How do you know what the fan speed should be? It would be wise to measure it whilst you've still got the PTO pump fitted. Consider fitting a speed sensor before you do the swap.

I guess a pressure gauge on the pump supply would be a very crude way of doing the same thing?

 

[Case290]

I’ve converted mine to hyd flow return loads better up to speed straight away you can buy my old pump if you like only did abit,

 

[Romeogolf]

The fan has a speed sensor on it which reads out on the control box, it’s not measure off the pto pump so should give an accurate reading regardless. I may be willing to part with it, however I did think of retaining it should an occasion occur when I didn’t have a tractor with 4 spools, however unlikely, I know it would be very difficult to buy one back in the event!

I’ve only ever had the fan running at 2500 on the display for wheat, is that not a true reading of rpm? I accept your point though, and agree float is the best option when running it down.

 

[Lincsman]

The fan has a speed sensor on it which reads out on the control box, it’s not measure off the pto pump so should give an accurate reading regardless. I may be willing to part with it, however I did think of retaining it should an occasion occur when I didn’t have a tractor with 4 spools, however unlikely, I know it would be very difficult to buy one back in the event!

I’ve only ever had the fan running at 2500 on the display for wheat, is that not a true reading of rpm? I accept your point though, and agree float is the best option when running it down.

I seem to remember 2700 rpm is the minimum required, on a 6m you would have blocking.

 

[rob h]

What are you going to do with the old pto pump ??

I'm after one to convert my drill back to pto driven rather than the spool..

Because mine is a mounted drill, the tractor won't lift it at the end of the row unless the spool is turned off - oil takes the path of least resistance..

Let me know if you want to part with it ...

We had the same problem with our miniflow.when we used it on our mf3670.also couldn’t take a bit of weight when going over wet patches.swaped tractor for a 6499 now with electric spools turned down I can lift and work markers with the fan still running