Gas vs Electric Engine: HP requirements

[Charles84]

I will be using the 35 HP Briggs Vanguard (not efi). It's only capable of electric start. I doubt i will ever use this machine in -5 degree weather as we only get a few days of 7-10 degree weather here in Central Va each year. Since i'm going to have to do a significant amount or wiring and rewiring for this job, I might look at including a 120v electric start like i've got on my Crafstman snowblower. The 120v electric start via electrical cord is the only way i can get that thing started any time.

I've been studying the PT425. They look like neat machines and the specs seem very similar to what i'm looking to do.

Right now it looks like 2 Hydrogear PR or PY Piston pumps in tandem mounted to the crank and 1 PR or PY mounted to a Flywheel stub shaft. I'm planning for a re Power and a 4wd Full track conversion of my JD 420. But i'm still in the early design stages and in no rush because i want to get this done right the first time. I'll start a new thread to document this once i get ready to start building.

Are you familiar with Lunchboxsessions.com? It's got some great free content regarding hydraulics and electrical, and then for $29 a month you can use all their resources which allows you to Study, and put together hydraulic components into a schematic type puzzle to test whether your system is functional.

Thanks for your replies everybody.

 

[Threepoint]

It kinda baffles me that when it comes to tractor specs, I rarely ever see torque mentioned.

Not to derail the OP's thread, but maybe it's because of so many variables in translating torque to a tractor's various capabilities. :confused3: I suspect there's also an understandable desire of the manufacturers' not to get too far down in the weeds if it would mean disclosing engineering design algorithms and assumptions.

Racenut, since you're shopping for a tractor, the following thread might interest you if you haven't already seen it. I started it, and learned a lot from the replies. https://www.tractorbynet.com/forums/buying-pricing-comparisons/416609-engine-pto-hp-rated-rpm.html

 

[Charles84]

Why 2 pumps for 4 wheel motors?
And why a variable speed for the FEL and backhoe?

How are you planning to turn it?

I would prefer to do variable speed for the FEL and backhoe for smoother operation of the equipment.

2 pumps for 4 wheel/sprocket motors. 1 pump for the left side, 1 pump for the right side. .I think the correct term would be connected via series, or parallel? 4 Wheel/sprocket motors because i want to have as much torque and power to turn and use it as a mini bulldozer as well. The terrain has lots of hills here also. I realize I'm going to have to have a larger reservoir/oil cooler/fan, which is also one of the reasons I want the backhoe /FEL to be on variable displacement so that It's not constantly cycling oil heating it uselessly. Luckily this JD 420 is large for a garden tractor so it's the perfect candidate, and i'm gutting it nearly completely to the frame to start from scratch (Traded for the JD 420 with a friend who had a significant amount already disassembled which he was going to restore until he found out it had a severely blown engine..which blew up 2 connecting rods, sheared part of both pistons, bent a valve and damaged the block!)

I will be turning with control valves. It will be a zero turn, not articulated like the PT.

 

[MossRoad]

How are you going to control the demand for more speed for the FEL when needed? That would require either an extra lever/pedal, or a very expensive/complex torque sensing setup to sense demand. Sounds like a great project. I'll watch for updates. Good luck. :thumbsup:

 

[Charles84]

How are you going to control the demand for more speed for the FEL when needed? That would require either an extra lever/pedal, or a very expensive/complex torque sensing setup to sense demand.

I'm not sure I understand what you mean by more speed. Could you elaborate?

 

[MossRoad]

I'm not sure I understand what you mean by more speed. Could you elaborate?

Variable volume pump on the FEL. How are you going to control the speed of the loader arms up/down and dump/curl? With the joystick changing the angle of the swashplate?

Think about FEL operations. There are 2.
1. up/down
2. dump/curl

How are you going to provide those 2 operations with only 1 variable volume pump? You can only change directions of one operation with a swashplate. You'd need two variable volume pumps for the FEL. One for up/down, and the second for dump/curl.

Mine is a fixed volume pump. The farther you push the lever forward, the faster the FEL arms lower. The farther you pull the lever back, the faster the FEL arms raise. Anything not used by the valve goes back to the tank, as it's open center. If the pump were variable volume, you'd need 1 circuit to control the up/down, 1 circuit to control the dump/curl, and one circuit to control the volume of the pump.

Perhaps I'm missing something?

 

[oldnslo]

I believe the hydro-gear pumps are closed loop or HST pumps. These will work for the travel drive but will not work well for any auxiliary functions like FEL.

 

[Charles84]

Thanks for the advice guys. I'll look into the FEL pump requirements further.

 

[MossRoad]

Thanks for the advice guys. I'll look into the FEL pump requirements further.

Just for knowledge, my PowerTrac has a 25hp Kohler. There's a variable volume pump on one side that feeds 4 wheel motors. Left front and right rear are in series. Right front and left rear are in series. Then those two series circuits are in parallel. On the other side of the gas engine there is a two section pump. One section supplies 8gpm @ 2500 psi and that is used to power any attachments like mowers, brush cutters, trenchers, tillers, brooms, etc... and it is activated with an electric solenoid and has motor spool function, so it lets motors coast when shut down. The other section supplies (as I recall) 4gpm @ 2500 psi, and it supplies power to the steering valve, out a power beyond port, to a 3 section valve bank that supplies the FEL up/down, dump curl, and aux PTO. The aux PTO is for things like power-angle snow plow, grapple jaw, 4-in-1 bucket... things like that, all cylinders, and no motors. Steering has priority over FEL and aux PTO functions.

So my setup uses the engine's standard shaft, plus a stub shaft on the other side. Newer models have the two-section pump piggybacked off of the variable volume tram pump, so everything is on one side of the engine. I suppose it saves on the cost of the stub shaft setup, at the expense of having to find a tram pump with the piggy back shaft for more sections.

 

[WranglerX]

Might want to get away for "tractor" specs and look at it in more of engineering concepts....

Hydraulics and Pneumatics

Dale