Adding a 2-speed pto

[rbargeron]

My L4150 had a 2-speed pto, 540 and 750, which was very handy - often I could save fuel, noise and engine wear by running the higher pto speed but with the engine at around 1800. Also, I could run my snowblower up a little to get better throw distance.

My L5450 only has single-speed 540 pto. So I run the engine at 2300 rpm or even higher, but would like a faster pto gear like I had before.

In going over the 5450 parts list, it shows that the tractors in this series made for Australia and New Zealand have 2-speed pto. I've compared the lists and by replacing 2 parts and adding three new ones, my rig will have both 540 and 900 (approx) pto speeds. The parts show as available so they were ordered today. We'll see if this works out.

Anyone have any experience with this? Kubmech?

1-21-02 update - the NZ gears give 900 rpm, and the Aussie gears give 750 (same as my 4150 had) so I'm going Aussie.

 

[kubmech]

No experience with this one. But very curious how you make out./w3tcompact/icons/cool.gif

 

[JimMorrissey]

Also very curious. It seems 900 rpm would put some tremendous stresses on a snowblower designed to run at 500+. Anyway, love to hear how it goes for the same reasons you described.....more blower speed at lower rpm.

 

[rbargeron]

This snowblower is very simple - it can run fast without trouble. It's rear-mounted, works going forward. A one-piece auger/impeller, running at pto speed, is the only moving part. At 540 rpm, it throws the snow about 5 to 10 ft. I've used it for years on tractors with 2-speed pto's. It works great at the higher rpm.

The new pto gears will give 540 and 750 rpm speeds. I decided against the 540/900 rpm gears because I'll use the higher speed for finish mowing too. At 540 on high, the engine can be down at 1700. With the 900 gears the engine would be at 1350, too slow for good power or governor response.

Other items that will run fine at lower engine rpm are a sickle-bar mower, pto generator, water pump, farmi winch.

 

[hwp]

If your snow blower is only throwing snow 5 to 10 feet, there is something major wrong, either the discharge speed is too low or there is too much leakage between the impeller and the drum. The discharge speed should be at least 5000 feet/min. This will throw dry snow between 80 and 100 feet. To calculate discharge speed multiply the rpm by the diameter of the impeller(in feet) and multiply by 3.14(pi). For example, I run my machine (a F2400) with the pto in low range at a speed of about 1000 rpm (engine speed is 2000 rpm), which is also my impeller speed. I have a 20" impeller so 1000x(20/12)x3.14 = 5230 feet/min. If you run your pto at 540 rpm and have an auger/impeller that is 2 feet in diameter, you will have a discharge speed of only 3400 feet/min. At 750 rpm, you will still only be at 4700 feet/min. Better, but still not great.

The other variable to look for is the clearance between the impeller and the drum. If this gets too large, there will be a lot of leakage and the blower won't be very effective. Single-stage snowblowers tend to have larger clearance between the impeller and the drum because of the larger mass that is being rotated and therefore the more difficult it is to hold tolerances.

I rebuilt my snowblower this past summer, including putting a new band inside the drum because I was getting a lot of leakage due to wear on the impeller blades and the drum was bowed out from too many stones. I ground the impeller blades to fit the new drum diameter, leaving 0.020" clearance. We have only had one small snowfall so I haven't had a chance to give it a good workout, but with the little bit of snow we had, it worked great - it threw medium wet snow about 40 feet.

I went to the shop where my snowblower was made and was told that for a two-stage snowblower, the impeller should pick up a dime from the bottom of the drum and carry it on edge to the point of dischage a quater turn later. I was also told that when it got to the point that the impeller could not pick up and carry a quarter, it was time to rebuild. I had over a quarter of an inch clearance so I rebuilt.

 

[rbargeron]

You're right on all points - sounds like you did a nice piece of work on your housing.

I know 750 isn't that much more, but it makes the needed difference. The throw distance of 5-10 ft is for heavy wet slushy stuff. Dry powder goes 20 feet even at 540. I know from experience that the 750 pto speed works like a charm with this blower - and with my other stuff.

Project update - using my lift, raised the back end of the L5450 up so pto is 56" off the floor - this pools the oil forward so the pto gearcase comes off without draining the trans. It sure looks nice in there - no wear marks on anything. Kubota painted the inside of the gear housings - nice quality touch. New gears are due to be delivered tomorrow.

 

[cedarranch]

Hope you document the process with LOTS of photos!
And post'em here! /w3tcompact/icons/cool.gif

 

[rbargeron]

Well I just finished cleaning the gasket surface on the tractor and the gearbox is off and all apart, waiting for the new pieces. Maybe I'll finally break down and buy a digital camera - naah.. maybe I'll borrow one. I've needed an excuse to buy one but the new gears are making a hole in my allowance. Kubota seems quite proud of them, judging by the price. /w3tcompact/icons/smile.gif

One positive sign is that the shifter rod has THREE detent grooves (as in low-neutral-high) and by taking out the travel limiter the drive collar now moves to all positions. This is going to be duck soup. Of course that's what JohnInCA thought about putting a Bradco hoe on his NH (over in Attachments)

 

[hayden]

I love the plan. Keep us posted.

 

[rbargeron]

Another item I noticed while disassembling the gearbox is the overall quality of the work Kubota does. Bearings and shafts are all "light press" fits - they all came apart with about the same force. Bearings are either light press or slip fit in their case bores - the slip fits are all near-zero clearance - very impressive consistency of fit and precision. To make machinery this way takes a commitment to quality through the whole company. The way their parts fit is hard evidence.

Ok, ok, I'll go find a camera. The 5450 looks funny with its back end in the air.