Old Toro Reelmaster Project

[Robert128]

The one joystick drops the decks and starts all five motors. - But I am only using the front 3. I wonder if those motors are going to be big enough. Thats why I am just building one deck (roughly) to see if the HP is enough. I found that the 3 front motors run in series (dont know if I am using the right terminology), the exit port from one motor goes to the input port of the next.

 

[Robert128]

Here is a schemata of the hydraulic system

 

[J_J]

Here is a schemata of the hydraulic system

R3 is a 1500 psi DPRV relief valve. Each motor develops about 7 HP. If you keep the blades light weight, you might get away with it. With 7 GPM, the blades are spinning at 1394 rpm. The third hose eventually goes back to tank. What did you do with the hoses once removed from the hyd motors? So the one valve is putting fluid to three hyd motors?

 

[Robert128]

Have not taken the motors off yet (From the back) Just have them hanging from a wire to get them out of the way. So these motors are running in series. Input motor, out of motor, into next motor... Running in a line.. last motor exits fluid back into seloid valve block, and then I guess back to tank.
The back motors are running in a similar loop, In series. So I am thinking of running the output line from the back (after the valve) to the output line in the front (After the valve). And then do the same for the return lines - So I will have enough capacity to handle the increased flow rate out of the return lines. -
I am trying to keep it as simple as I can because a lot of these lines are connected as shown on the schemata. - So I would not be changine anything else - Just one input and one output.

 

[J_J]

The relief valves across the motors is 3000 psi, so I am assuming that the pumps are 3000 psi pumps.

In a series hyd motor circuit, the pressure is divided across each of the motors, so in a three hyd motor configuration, each is getting the same GPM, but the 3000 psi, is divided, and the load is represented by each motor, develops 1000 psi. In a parallel circuit, the pressure is the same if the load is equal, but the GPM is dropped across ever how many motors in the circuit.

Since you have two 7 GPM pumps, why not power 2 hyd motors in series with each pump.

In a three motor series configuration, each motor is developing 1000 psi, and developing about 185 in lbs of torque.

In a two motor series configuration, each motor is developing about 1500 psi, and about 277 in lbs of torque.

In a single hyd motor configuration, the hyd motor is developing 3000 psi, and about 554 in lbs of torque.

Did you say one valves control all 5 motors.

You did say that the hyd motors were 1500 psi motors.

 

[Robert128]

Only using 3 motors. Yes, One stick controls all five motors and hydrualic lifts. It is programmed sequence - All electronic. No Linkages at all on this machine.

 

[mmurphy]

Robert128,

You mentioned a tree shear. Here is a home made tree shear that I made, and the next one is by Power-Trac. I also have a hyd chainsaw that could be mounted on a boom.

Rest assured that the small line from the hyd motors is a hyd case drain, and can not be restricted in any way. It would be the same size if it had to do with the speed of the motor. I have case drains on my hyd wheel motors, and the drains are conected to a manifold, which is a common collection point. and then on to tank.

JJ, that is an awesome looking machine. Have you ran a U-tube video of that in action? I take it you also have other attachments for that.

 

[RJA.Ilex]

JJ the extra power requirement of a rotary is down to the pumping action of the blades and a less efficient cutting action, hence a greater power requirement. The rotaing mass on a rotary mower is normally less than that for a cylinder but a rotary has tearing action similar to a blunt knife. Studies in the UK from the 70s showed that a knife edge radius of ~1.5mm provided the best compromise between knife life and cutting performance. A cylinder mower has a scissor like cutting action which is more effective.

Robert128 The power loss you mention when you tested a single deck was probably due to the relief valve blowing off(can you adjust the setting?). I experienced this while doing development on a 6 foot rotary deck. Check your blade speed and aim for a tip speed of ~13000ft/min lower than this leads to a decrease in cutting performance but I have not managed to find any reports that cover a higher tip speed but know this is what Ransomes and Toro aim for on this kind of machine (a legal limit in some areas). If your decks are trying to turn faster than this then I would suggest you change the motor sizes to increase torque. Can you plumb the two pumps into a single line to increase the flow available? or change the pumps for a larger single one? I believe you said theengine was a 38hp unit earlier this is plenty for what you are trying to achieve but you need to get it to the decks. Also keep the rear of the cutting deck as open as possible to reduce the energy needed to dispose of cut grass.

 

[J_J]

Robert128,

If 3000 psi is sent to a 1500 psi motor, It will probably run, but half the pressure or 1500 psi will be relieved by the relief valve. The valve will certainly heat up. Since it is relieving, it is also taking away from the 7 GPM that is generated by the pump. Two motors in series will give the best efficiency, and life cycle. I don't think there is enough torque on three motors in series to make it worth while.


P1--7 GPM @ 3000 psi= 14 HP
P2--7 GPM @ 3000 psi= 14 HP
P3-- 4 GPM = 1250 psi = 3 hp
P4--26 GPM @ 4000 psi= 71 HP

Things are not adding up as the the total use of the 38 HP engine. With all the pumps working, total pump output is 44.5 GPM,

A 38 HP engine should only be able to provide enough HP to run 18.5 GPM at 3000 psi.

There is something missing somewhere. Maybe my math is flawed. How about someone else double check my numbers.

 

[ray66v]

I don't know which Reelmaster he has, but my 5100 is only 23hp.

I do not know of a 38 hp reel model.