post knocker

[chriss]

can anyone tell me if my 55 major will run a parmiter post knocker

[shazbat]

Hi Chris,

Yes, but only using your extra spoolvalve, that I note you recently fitted - the other one will lift the TPL first then the knocker - not advisable...
Also make sure your oil has warmed up and your knocker mast is well greased otherwise it might struggle to lift it, similarly if the seals on the knocker ram aren't 100%.

Hope this helps,

Shazbat

[chriss]

yes thanks for that, have ordered new ram today as seals were leaking everything else on the knocker is well oiled and free running am thinking of changing oil and cleaning filter to give everything the best chance.

[chriss]

fitted new ram today but hydraulics still wont move the weight more than 1 1/2 inches any ideas please

[shazbat]

A 55 major should have 90 grade oil in it (and before anyone jumps in to correct me, I know a lot of people use universal 40 grade which is a lot thinner) anyway 90 grade is pretty thick and consequently really should be worked/warmed up and therefore thinner and easier to pump around before using in anything meaty like a knocker or log splitter. A pressure test would be a good idea, this would tell you if the pump was OK. It could also be the pressure relieve valve - depending on the state of this, an old tanner - or a washer - between the valve head and the cover might help.

Hours of fun these old majors!

[chriss]

just picked up new oil will change today malcom hipperson has lent me a pressure gauge so hopefully i'l see if there's good pressure to the ram

[chriss]

changed oil cleaned strainer put pressure test on needle shot straight to 2000psi then fell back to 500

[shazbat]

Then I reckon it's the pump or thr relief valve - try the washer trick under the valve cover - if that doesn't help then it's still either the pump or the relief valve.
Pumps can be got hold of on Ebay - not sure about the relief valves though.

[chriss]

is it worth putting the gauge on the lift arm valve just to see if i've got something wrong with the new spoolvalve

[shazbat]

The same thing should happen. If it doesn't then this has me confuddled - which doesn't take much nowadays...

[Brian]

There is nothing wrong with the pump, that is exactly how the pressure works on a Major, the relief valve opens then the pressure drops. You then have to lower the lever, which re-seats the valve, and start again. That is the nature of the beast. The idea is to prevent the pressure reaching the 2000 psi. When you have your oil going to the knocker ram there is a restriction that is causing the pressure to rise enough to unseat the unload valve before work is being done.

You will see in another thread that it is suggested that the pressure setting on the relief valve on a double acting valve chest is set to around 1500 psi so that the implement can work constantly rather than having to keep resetting the lever.

The unload valve in the valve chest on the tractor could be one of the earlier units in a 1955 tractor. These were not as good as the later valves fitted to the Power Major which was designed to re-seat faster.

It is possible that your post knocker has small pipes designed for later tractors. If so and you have 90W oil in the rear axle, you could be reaching the unload valve pressure release point before you have done any work. The oil will need to be fairly warm to flow through the small bore pipes as has already been mentioned.

The lift on the tractor is not very sophisticated, it was only really meant to lift implements on the lift arms not power external implements. This is why on later tractors after 1958 the oil spec was changed from 90W to 30W, to enable an easier flow and less resistance through the small holes in the lift valves.

It should be possible to get your knocker to work though, look to avoid sharp bends in the pipes and, if you are using push in connections, Doughty or Exactor couplings, you may need to connect your pipes straight to the tractor without these items. I have come across cases where these couplings restrict the flow on modern equipment using much lower viscosity oils at higher flow rates.

[chriss]

thanks for that as it happens the connector on the flexi pipe is a blanked off t so forming a90 bend with a dowty fitting plus a push fit connector so this must be creating too much pressure befor it reaches the ram

[chriss]

got the hammer moving today a little at a time but the old major didn't like it much so the knocker is now on ebay