Hydraulic Pump Question

[Tombro]

I have a Jacobson mower, formerly a 3-gang reel type. The reels were powered from a 3-gang belt driven pump. The reels were removed and a rotary deck (72") was attached instead. I acquired it in that un-finished state. My question is regarding the triple pump, can the pumps be run in series or parrallel in order to provide enough volume to run a single motor? I need to get a blade speed of about 12000fps on three belt-driven blades on the single deck drive pump.

I suppose an alternate may be to replace the 3-pump unit with a single of appropriate size.

I'm kind of lost and will appreciate any input or referrences.

Tom in WA

 

[Anonymous-0]

You should be able to combine flow but a rotary will take more flow and use more power than a reel mower. Find out what pressure the relieve is at as well. A mechanic that worked at the same place as my dad (Toro distributor) designed and built a combining valve for early Toro sand pro's to take the flow from the front wheel and add it to the rear wheels for faster transport speed between sand traps. Once there, it was switched back for 3 wheel drive. The newer models had a faster transport speed that might have been copied from this in house design. If it was only a 3 gang mower, a 72 inch deck might be too big. There are some hydraulic drive rotary's that you can get specs. from. Jacobsen had a hydraulic drive turf cat and Toro has some hydraulic drives as well. You may need an additional oil cooler as well. What type of reel mower was it? If it was a Greens King, you'll be low on power. What engine? A lot of the older stuff used Kohler engines in the 12 and 14 HP range. Hope this helps. Dave

 

[Anonymous-0]

I am guessing a little bit but probably each section was used to raise and lower each gang! If so the continous running of a hydraulic motor will heat up the oil rather quickly. As was mentioned below you will probaly need a cooler as well as a larger reservoir to aid in disappating the extra heat generated. I don't know what control valves you have now. You will need one section to raise and lower and a section with a "motor spool" to run the motor or a cross relief to protect the motor. Power was mentioned. Old rule of thumb for practical; purposes: It takes 1 Horsepower for each one gallon of flow at 1500 PSI. Also pumps and motors are all rated at theoretic 100% effecinency. None are 100%. You need to factor that in as well. More questions? J.

 

[Tombro]

The engine is a Textron 16.5HP diesel, the mower is a Jacobsen Tri-King 1671D.

The wheels and the blade lift (not used now) are driven from the hydrostatic pump directly off the engine. The former reels were driven from the auxillary belt-driven pump controlled through an electric clutch on the engine. I don't know what the relief is set at.

In reading around it looks like I'll need to measure/calculate the pulley sizes for the deck drive and the three driven shafts in order to guestimate the HP/RPM needed.

The engine and drive systems work fine.

My father-in-law, whose failing knees prompted him to give this to me (I have 3 acres to mow), had built a combining manifold for both the supply and return lines (3 each). Whatever motor he adapted to the deck turned, but very slowly and un-usable.

He is an old-school seat-of-the-pants mechanic and does not do math. He suggests that I just mount an auxillary engine to the deck and get to work, but I'd prefer to be a bit more integrated (and quiet) with it.

 

[Anonymous-0]

Flow (pump output) determins motor speed. Either your motor is too large in cubic inches of oil per revolution or the combined output of the pump(s) is way too short. Or a combination of the 2. How large is the reservoir?

 

[Anonymous-0]

You're going to be low on power for a 72 inch deck in all but the shortest of grass. The Tri-King is basically a newer model Turf-King with hydraulic drive reels instead of the older belt driven mechanical reels. A reel mower usually cuts grass very often so it never gets too tall. The hydraulic motor for turning them is a pretty small aluminum housing. A motor for a 72 inch rotary is a large heavy duty motor and probably cast iron. A reel won't need near the torque or h.p. that a rotary needs. Also a belt driven pump could slip under load. I don't think you'll have enough oil flow. Go to a Jake or Toro commercial dealer and get some literature on new mowers. It should have some specs. for what you need. Also talk to the mechanic. Golf course equipment are huge users of hydraulics because of the simplicity in designing around it. Do you have the original reels? If your grass is fairly nice with no dirt or pebbles etc. a reel could still work for you. Dave

 

[Anonymous-0]

I thought of this later. My customers have some 6 foot rotaty choppers. They run them with a Commercial P-51 pump. Your little diesel will not do it. They take about 30 horsepower the way they run them.

 

[Tombro]

Thanks for all the input. Doing the math it looks like I could get a new pump that may demand about 6-8 HP (of the 16 rated) and a new motor to achieve a blade speed of around 18Kfpm. I have not figured all the friction of the system but imagine that I can still afford some horsepower with enough to motivate at a reasonable speed.

 

[Anonymous-0]

It takes more than 6 to 8 HP to run a 72 inch rotary mower. I hate to be the bearer of bad news but I think you'd be spending a bunch of money on something that you'll be very disappointed with. You'll never be able to lift the deck up. The back wheels would be 3 feet in the air. How are going to sharpen or change blades? Where will you mount the extra capacity hydraulic tank and oil cooler? Getting a fast enough motor is only one part of the design. You need to have a high enough horsepower and torque motor as well. If you had all 16 HP of the engine available for the deck would still be low in all but very short grass. Like I said, go to a commercial mower dealer and check on some specs. of mowers that are already made. They are designed by experienced engineers. They can have some problems but usually the HP and oil flow are figured out correctly. Dave

 

[Tombro]

Thank you, Dave. It is a bit frustrating, I trusted he knew his stuff having been a diesel mechanic and machinist for so many years. And I paid him $400 for the machine (originally was to be $1000 for the working mower). You are right I think also about lifting the deck, he was abandoning the lift as I have flat ground but I'd like to lift it. Sharpening is not a big deal as I could use a hoist for that.

On another topic, by your handle we have similar tractors. I have an MF20 that lived its life as a fairway mower. It had a Ransomes mower on it and was well maintained until somebody noticed a "banging" under the seat and they used that as an excuse to purchase a new mower (small po-duck golf course). It turns out the banging was the hydraulic pump relief valve operating normally. I paid them $500 for the tractor/mower.

Know anybody that wants a 12' wide, 7-gang reel mower?

Tom

 

[Anonymous-0]

Don't know anyone who needs a pull type reel mower. You should see if a commercial dealer might sell it on consignment? Maybe they have a used machine you could trade it in on? Ransomes were never too popular up here but I think Textron owns them along with Jacobsen. I have a cab off an MF20 on my UK 135 diesel. No floor boards because UK models are 3 inches lower than US models. I looked on the Jake site. All the rotary's are hydraulic. The smallest one is 26 HP with a 60, 63 and 72 inch deck available. I would guess that the 72 inch is only recommended for grass that is kept short and mowed very often. Another engine to power the deck could work but that's a lot of work too. Maybe you could find a used 48 to 60 inch deck? That might work but still be a lot of work to figure out. Dave