Hi-Flow Conversion

[Tazza]

Hello guys. I have a 743B with aux. How hard would it be to add one to mine? TheTool THANK YOU for posting this. I am very new to bobcats. I will be keeping this machine for some time so to me it looks to be a viable investment. God Bless Sam French

Technically it could be done, but i believe its a waste on your machine. You would need new aux hydraulic lines from the quick couplers to the control block. Then i don't know if the control block could even handle the extra flow. Hi-flow is only needed on a select few attachments, most work fine with standard flow. Most of the ones taht require hi-flow need the electronics on the newer machines anyway. I don't know how you would attach the pump too, they usually attach to the end of the main pump or to the end of the crank, both ends will cause problems with room.
Just my 2c at least.

 

[renopker]

Technically it could be done, but i believe its a waste on your machine. You would need new aux hydraulic lines from the quick couplers to the control block. Then i don't know if the control block could even handle the extra flow. Hi-flow is only needed on a select few attachments, most work fine with standard flow. Most of the ones taht require hi-flow need the electronics on the newer machines anyway. I don't know how you would attach the pump too, they usually attach to the end of the main pump or to the end of the crank, both ends will cause problems with room.
Just my 2c at least.

Cant I just add a bigger center cartage on the Hyd.pump and larger aux lines (snow blower) and pick up extra 4-5 gpm will that do it?

 

[Tazza]

Cant I just add a bigger center cartage on the Hyd.pump and larger aux lines (snow blower) and pick up extra 4-5 gpm will that do it?

You will still have a restriction at the control block, i don't know what they are designed to handle, I'd suspect a bit more than the standard. The other concern I'd have is the strength of the shaft from the engine to the pump. Install a larger pump you will increase the load. The engine may also not have the HP to drive the larger pump AND drive at the same time. There are a few factors to consider, I'm sure it would work, but you just need to watch a few things.
I'd never dare say it CAN'T be done, as i know the abilities of some of the people around here and they could do it. If it works as hoped is another question all together.
If you decide to give it a go, make sure you take LOTS of pictures for us, it will make for an interesting project indeed. I'd suspect the first Hi-Flow 743 around these parts

 

[thetool]

You will still have a restriction at the control block, i don't know what they are designed to handle, I'd suspect a bit more than the standard. The other concern I'd have is the strength of the shaft from the engine to the pump. Install a larger pump you will increase the load. The engine may also not have the HP to drive the larger pump AND drive at the same time. There are a few factors to consider, I'm sure it would work, but you just need to watch a few things.
I'd never dare say it CAN'T be done, as i know the abilities of some of the people around here and they could do it. If it works as hoped is another question all together.
If you decide to give it a go, make sure you take LOTS of pictures for us, it will make for an interesting project indeed. I'd suspect the first Hi-Flow 743 around these parts

Hmmm.....
I think if I was going to build hi-flow onto a 743, I can imagine mounting a pump to the PTO off where the fuel pump is, like a tractor set-up.
I would then pumb into a manifold with an adjustable flow divider, relief valve, and electrically-activated control valve. I would mount a button on top of the left stick, click-on, click-off.
Then I would relace the tubelines with larger tubes or even hoses, and tee into the line going to the female or bottom coupler from the diverter, with a check valve.
With all that adjustable flow and relief, then I would see what I intend to run and do some math to get close, then dial it in under operating conditions. I cannot imagine a 743 being able to handle more than an addtional 6-8 gpm, but that really depends on the operating pressure of the attachment.
If you could hook a pump to the spot where they mount pumps on tractors(I'm blind and dumb here, now) I think you could solve the room problem with that approach. Return plumbing would have to tee into someplace that would for sure hit the filter and cooler, but teeing into the line going to the coupler would by-pass the control valve and eliminate the back-up there. You can't have high-flow in both directions unless you run it all through the main control valve.
So then with this set-up I guess I would want a way to disable the hi-flow button in reverse.
I imagine sitting in the seat, shifting the lever for normal flow, then hitting the button for high. Maybe an indicator light in the dash so you know when it's on, and don't inadvertently over-flow a standard attachment.
Very custom. Practically, probably more of a conversation piece, but I'd like to know what you're wanting to run with a high-flow 743? Sounds like fun, whatever it is.

 

[thetool]

Hmmm.....
I think if I was going to build hi-flow onto a 743, I can imagine mounting a pump to the PTO off where the fuel pump is, like a tractor set-up.
I would then pumb into a manifold with an adjustable flow divider, relief valve, and electrically-activated control valve. I would mount a button on top of the left stick, click-on, click-off.
Then I would relace the tubelines with larger tubes or even hoses, and tee into the line going to the female or bottom coupler from the diverter, with a check valve.
With all that adjustable flow and relief, then I would see what I intend to run and do some math to get close, then dial it in under operating conditions. I cannot imagine a 743 being able to handle more than an addtional 6-8 gpm, but that really depends on the operating pressure of the attachment.
If you could hook a pump to the spot where they mount pumps on tractors(I'm blind and dumb here, now) I think you could solve the room problem with that approach. Return plumbing would have to tee into someplace that would for sure hit the filter and cooler, but teeing into the line going to the coupler would by-pass the control valve and eliminate the back-up there. You can't have high-flow in both directions unless you run it all through the main control valve.
So then with this set-up I guess I would want a way to disable the hi-flow button in reverse.
I imagine sitting in the seat, shifting the lever for normal flow, then hitting the button for high. Maybe an indicator light in the dash so you know when it's on, and don't inadvertently over-flow a standard attachment.
Very custom. Practically, probably more of a conversation piece, but I'd like to know what you're wanting to run with a high-flow 743? Sounds like fun, whatever it is.

Or right stick, I should say.......oh man, whichever stick you use for the aux......=). Yeah, THAT stick....

 

[Tazza]

Or right stick, I should say.......oh man, whichever stick you use for the aux......=). Yeah, THAT stick....

hehe, sounds you have been drinking some good stuff there Shane
I was wondering just how strong the PTO on the engine is, i'd hate to have a pump running and something happen to cause the injector cam to snap. I'd be careful with how much load you put on that shaft, i don't know if the gearing is designed to handle a lot of load that a pump would put on it. But with saying that, they put it there for a reason! its not there just for show.

 

[renopker]

hehe, sounds you have been drinking some good stuff there Shane
I was wondering just how strong the PTO on the engine is, i'd hate to have a pump running and something happen to cause the injector cam to snap. I'd be careful with how much load you put on that shaft, i don't know if the gearing is designed to handle a lot of load that a pump would put on it. But with saying that, they put it there for a reason! its not there just for show.

I am referring to doing this on the 642 I'm working on,I think the pumps are the same and buy adding a larger cartridge to the hyd. pump to pick up the extra flow, theres no need to for the extra work of mounting a extra pump.As soon as I reach that point Ill dig out all the info on the flow of the aux.lines,a divider valve and other stuff need to do this.At this time IM working on a post hole auger and I will post pic in the near future.

 

[skidsteer.ca]

I am referring to doing this on the 642 I'm working on,I think the pumps are the same and buy adding a larger cartridge to the hyd. pump to pick up the extra flow, theres no need to for the extra work of mounting a extra pump.As soon as I reach that point Ill dig out all the info on the flow of the aux.lines,a divider valve and other stuff need to do this.At this time IM working on a post hole auger and I will post pic in the near future.

On a older model like a 642 you could likely up the ci of the cartridge and increase your std flow volume, so long as you have the hp in the engine to handle the load. However the whole point of 2 pumps is that usually you don't need high flow, and further if you directed all the flow though you valve body your boom and tilt speed would increase also, for better or worse.
For the sake of attachment that don't need hi flow and for keeping the boom cycle at the designed speed, the flow of the second hi flow pump is only directed to the aux quick couplers, then only there when hi flow is activated for the attachments that need it. Putting hi flow to a grapple or a 4 in 1 bucket would be a exercise in ex-aspiration, as the function would be way too fast. Though not as bad on a model where the aux spool is controlled by a manual linkage.
On the 753 etc with electric over hydraulic for the aux couplers it would truly drive you nuts, you would need a very restrictive fitting to control the speed of the cylinder and a lot of hp to push all the excess oil over the relief valve at max pressure, burning fuel and creating heat for nothing.
Ken

 

[thetool]

On a older model like a 642 you could likely up the ci of the cartridge and increase your std flow volume, so long as you have the hp in the engine to handle the load. However the whole point of 2 pumps is that usually you don't need high flow, and further if you directed all the flow though you valve body your boom and tilt speed would increase also, for better or worse.
For the sake of attachment that don't need hi flow and for keeping the boom cycle at the designed speed, the flow of the second hi flow pump is only directed to the aux quick couplers, then only there when hi flow is activated for the attachments that need it. Putting hi flow to a grapple or a 4 in 1 bucket would be a exercise in ex-aspiration, as the function would be way too fast. Though not as bad on a model where the aux spool is controlled by a manual linkage.
On the 753 etc with electric over hydraulic for the aux couplers it would truly drive you nuts, you would need a very restrictive fitting to control the speed of the cylinder and a lot of hp to push all the excess oil over the relief valve at max pressure, burning fuel and creating heat for nothing.
Ken

I think there is a lot of conjecture about fantasy hi-flow machines going on in this thread, and I have been a major contributor........=).
As far as putting a larger ci cartridge in the existing pump, I would not even got there. The pump displacement by design is already pretty maxed out, there are a lot of things that tie into it, like the engine hp, engine cooling, hydraulic cooling, etc.....changing the ci of the hydraulic pump opens a HUGE can of worms. Besides, 642's and 743's are mostly vane-pumps anyways?
Tazza or anyone else-I wonder what kind of flow and pressure they're running on tractor hydraulics pto from the fuel cam?
A high-flow has to have a separate circuit that by-passes the main control valve and goes right up the pipe to the coupler. period. Anything else causes problems. Anything cheap is anything else.
That's why I made my project a factory high-flow. There is no down and dirty, cheap alternative that I can think of......=).
Dosen't mean there isn't......=). It's still fun to think about. Fun is not always practical, lol.

 

[thetool]

I think there is a lot of conjecture about fantasy hi-flow machines going on in this thread, and I have been a major contributor........=).
As far as putting a larger ci cartridge in the existing pump, I would not even got there. The pump displacement by design is already pretty maxed out, there are a lot of things that tie into it, like the engine hp, engine cooling, hydraulic cooling, etc.....changing the ci of the hydraulic pump opens a HUGE can of worms. Besides, 642's and 743's are mostly vane-pumps anyways?
Tazza or anyone else-I wonder what kind of flow and pressure they're running on tractor hydraulics pto from the fuel cam?
A high-flow has to have a separate circuit that by-passes the main control valve and goes right up the pipe to the coupler. period. Anything else causes problems. Anything cheap is anything else.
That's why I made my project a factory high-flow. There is no down and dirty, cheap alternative that I can think of......=).
Dosen't mean there isn't......=). It's still fun to think about. Fun is not always practical, lol.

Oh yeah tazza-you know, I'm not a drinker. Alcohol is so very, very evil. I was huffing ether.

 

[Tazza]

Oh yeah tazza-you know, I'm not a drinker. Alcohol is so very, very evil. I was huffing ether.

LOL good 'ol ether fumes
Those were my concerns as well, the 642 runs an even smaller engine than a 743 i believe, same frame size though. It still have enough power for what it does, but the newer machines have just that bit extra so they can handle a bit more engine load.
There was a gear pump option, but i think from factory they were ALL vane pumps. Throwing a larger pump cartridge at it to an extent i see no problems but there will be bottle necks with the higher flow in some parts, this will cause heat and extra engine load even when you aren't using the hydraulic functions.
I'd never say do it, or advise to do it, its your choice if you give it a go, but be prepared for possible problems in the future.

 

[renopker]

LOL good 'ol ether fumes
Those were my concerns as well, the 642 runs an even smaller engine than a 743 i believe, same frame size though. It still have enough power for what it does, but the newer machines have just that bit extra so they can handle a bit more engine load.
There was a gear pump option, but i think from factory they were ALL vane pumps. Throwing a larger pump cartridge at it to an extent i see no problems but there will be bottle necks with the higher flow in some parts, this will cause heat and extra engine load even when you aren't using the hydraulic functions.
I'd never say do it, or advise to do it, its your choice if you give it a go, but be prepared for possible problems in the future.

The 642 is rated at 32hp and looking at the room next to the motor theres plenty of room to mount and run a pump off the front of the motor and will make for a simple hyd.circuit.I will be running a snowblower and will need the extra flow.

 

[skidsteer.ca]

The 642 is rated at 32hp and looking at the room next to the motor theres plenty of room to mount and run a pump off the front of the motor and will make for a simple hyd.circuit.I will be running a snowblower and will need the extra flow.

On the NH there was a plug in the hydraulic valve for hi flow pump oil to join the flow after the second spool, #1 and #2 were for the boom. This way the 2nd pump only went to the couplers. Also when spool 1 or 2 is working the boom the second pump continues to supply the attachment by itself (as opposed to combined with the first)
If you go over about 20 gpm you should have 3/4" lines and couplers for the boom. You would also want to keep a eye on oil temps as some hi flow machines get bigger coolers (may not be a concern if you are in the snow belt or using it in winter only)
I would send the flow from the standard pump to a electically controlled valve and combine it with the second pump there, if you plumb it all into the original 3 spool valve you will want to check the back pressure it be sure the valve can handle all the flow.
Ken

 

[skidsteer.ca]

I think there is a lot of conjecture about fantasy hi-flow machines going on in this thread, and I have been a major contributor........=).
As far as putting a larger ci cartridge in the existing pump, I would not even got there. The pump displacement by design is already pretty maxed out, there are a lot of things that tie into it, like the engine hp, engine cooling, hydraulic cooling, etc.....changing the ci of the hydraulic pump opens a HUGE can of worms. Besides, 642's and 743's are mostly vane-pumps anyways?
Tazza or anyone else-I wonder what kind of flow and pressure they're running on tractor hydraulics pto from the fuel cam?
A high-flow has to have a separate circuit that by-passes the main control valve and goes right up the pipe to the coupler. period. Anything else causes problems. Anything cheap is anything else.
That's why I made my project a factory high-flow. There is no down and dirty, cheap alternative that I can think of......=).
Dosen't mean there isn't......=). It's still fun to think about. Fun is not always practical, lol.

Tool
Most engines that drive pumps of the front gear train (cam gears) have a spec for the amount of hp the gears can stand. Of couse the system pressure and flow would result in a figure that must be below that spec
Ken

 

[Tazza]

Tool
Most engines that drive pumps of the front gear train (cam gears) have a spec for the amount of hp the gears can stand. Of couse the system pressure and flow would result in a figure that must be below that spec
Ken

Ken - that was my fear too, you don't want to snap your injector cam or put excessive load on the gears that could cause damage.
This will be an interesting modification, take lots of pictures.

 

[thetool]

Ken - that was my fear too, you don't want to snap your injector cam or put excessive load on the gears that could cause damage.
This will be an interesting modification, take lots of pictures.

Yeah Ken and Tazza-
My fantasy custom 743 hi flow set up would have a diiverter with a relief valve, to protect that cam....=). There must be some hp safely available because tractors run that set-up. When designing it a guy would need the specs from a tractor that had a similar engine, then you work up hp, and calculate backwards and see if you were going to have what you need at the coupler to run what you got.
Practically, it's ALL fantasy to me, but the fuel-cam PTO set-up seems the most realistic if it were to be done.
Installing a larger ci pump seems to me a futile experiment, the best case outcome would be that it was removed before you burned up or broke something, and that you would have a relatively expensive pump that you could set on the coffee table as a conversation piece.....=)
I'm done beating this dead horse.....but it was my thread and I will try now and get in the last word.......=).

 

[renopker]

Yeah Ken and Tazza-
My fantasy custom 743 hi flow set up would have a diiverter with a relief valve, to protect that cam....=). There must be some hp safely available because tractors run that set-up. When designing it a guy would need the specs from a tractor that had a similar engine, then you work up hp, and calculate backwards and see if you were going to have what you need at the coupler to run what you got.
Practically, it's ALL fantasy to me, but the fuel-cam PTO set-up seems the most realistic if it were to be done.
Installing a larger ci pump seems to me a futile experiment, the best case outcome would be that it was removed before you burned up or broke something, and that you would have a relatively expensive pump that you could set on the coffee table as a conversation piece.....=)
I'm done beating this dead horse.....but it was my thread and I will try now and get in the last word.......=).

The cam and pump only turn at half speed it would have to come off the crank.

 

[Tazza]

The cam and pump only turn at half speed it would have to come off the crank.

Not if you run a gear pump. Vane pumps need the higher speed, but gear pumps are happy to run at lower speeds....

 

[renopker]

Not if you run a gear pump. Vane pumps need the higher speed, but gear pumps are happy to run at lower speeds....

So a gear pump will pump the same volume at half the rpm ?

 

[Tazza]

So a gear pump will pump the same volume at half the rpm ?

If the size is correct, yes. They will be rated in CC/revolution. If you can calculate the revs it will be doing and the CC/rev to work out GPM you can work it all out. But you will need to watch the load on the injector cam that you will be driving off.
It will be an interesting mod.