Just found out bout my David Brown tractor

[FarmboyBill]

Its a 1969, and it has live PTO/Hydraulics via 2 stage clutch, whatever that means.

Question. Neither the power steering NOR the hydraulics have gauges on the inside of there caps to tell how full to get them, is that supposed to be? How do I know when Ive got them full?

[DaleK]

I'm thinking there's a separate dipstick on top of the gearbox for the hydraulics

[fordy]

...............Could be the tractor has one internal pump that powers all the hydraulics ! On some tractors you unscrew the fill plug and fill it till it is just below the bottom edge of the fill plug threads . kinda like you do on a vehicle differential . , fordy

[COWS]

Not familar with the PS pump on that tractor, but amybe an inch below the level of the cap would be ok. Is the hydraulic fluid also the transmission oil? You need to leave some room for expansion when the tractor heats up, but your best bet is to get an operators
manual. You might check the Yesterday's Tractors website.

A two stage clutch means that the flywheel is two faced, that is it is machined on both sides for a clutch to engage. One side operates the motion of the tractor, the other operates the pto. There is a seperate lever somewhere to engage/disengage the gears for the pto and the pto clutch stops/starts the pto shaft. If the gears are not engaged the pto shaft does not turn regardless of the position of the pto clutch. It is common for that type of pto set up to have a ground speed pto, in which case the pto works when the forward motion clutch is engaged, or when the transmission is in neutral and the clutch is out. Lets suppose you are operating a small square baler and it plugs up. You can engage the ground sped pto in reverse gear, back the tractor slightly, and the baler will reverse briefly, hopefully loosening the plug. Supposedly if you are operating a pto post hole digger and it stalls on a root you can very briefly reverse the digger and loosen it. Never tried it, my luck was to break a universal joint in the digger's drive shaft. Those are the only 2 uses I know of for the ground speed pto setting.

The original 2 stage clutch thing came out in the mid 1950s in the Fergueson 35. It was controlled by the foot clutch which had 2 stages. AIRC the Case David Browns had a hand lever which controlled the pto clutch, making the system work like an independent pto system. The original independent pto system that came out in the Cockshutt and Oliver tractors was much better. They have a constant running pto shaft with a separate small clutch which operates the pto independently of the foot clutch and the transmission gearing. I don't know if your David Brown has the foot cluch controls or if it has the separate hand lever as described above.

The basic mechanism by which this works in either system is that the tractors have a hollow drive shaft in the transmission with another shaft inside the hollow one. I think the inside shaft operated the pto but I'm not sure.

Live hydraulics are another issue. Older tractors like the 8n Ford and the early 2 cylinder John Deeres had the transmission shaft driving the hydraulic pump. The Ferguesons did also and in the Fergueson 35 they let the constant running shaft turn the pump which was inside the transmission housing and hard to get to. Later tractors drove the pump off the distributor drive(late 1950s 2 cyl John Deeres) or on the side of the motor running off the timing gear drive. Your David Brown may or may not have the later system, I don't know.

COWS

[FarmboyBill]

It has the foot clutch.

[jwal10]

If I remember correctly the trans fluid had an "eye" on the left side of the housing. You could see the level through the glass. I was thinking the power steering had a dip stick under the cap. May have been a 780 my B-I-L had. 2 stage PTO, if you push it all the way down it disengages both PTO and transmission, part way down stops the tractor movement but the PTO still runs....James

[just_sawing]

my 990 has a dip stick on the left side and fill on the right. The power steering your fill to the top (Close but not over full)