F.E. Myers Air Blast Orchard Sprayer Information

[r8f1k]

My FMC sprayer had a 3 cylinder piston pump. Just watch your pressure guage as you’re tank gets low, when it starts to flutter shut the pump off . Running it dry after spraying a load for a few seconds shouldn’t hurt, just don’t drive all the way back to refill with it running.
The centrifugal pumps used in some sprayers are the type you’ve really got to be careful not to run dry.

I think the longest it has been run with little to no water was probably 1 minute while it initially primed.

In the searching I am doing, I have found that 2.25" piston cups are very common. My cylinder liners are 2". Is it possible that there should be 2.25" piston cups installed in this unit, giving a 1/8" on each side of "squish"? The piston cups that are currently in the unit are EXACTLY 2", but were they originally 2" or are they worn down to the cylinder sleeve?

 

[Seven Gables]

I think the longest it has been run with little to no water was probably 1 minute while it initially primed.

In the searching I am doing, I have found that 2.25" piston cups are very common. My cylinder liners are 2". Is it possible that there should be 2.25" piston cups installed in this unit, giving a 1/8" on each side of "squish"? The piston cups that are currently in the unit are EXACTLY 2", but were they originally 2" or are they worn down to the cylinder sleeve?

I’d think if ordered them for your model pump and supplier knew the cylinder diameter they’d of sent the correct ones.
Been 30 plus years since I put a set of cups in my old FMC but I do remember when new they were a little larger than the bore of cylinders. That’s why I softened them in boiling water, still had to drive them in with the special tool and hammer.
Are you having trouble getting and holding pressure? When you put the new ones in we’re they real snug fit like I described?
I’m 99% sure you haven’t ruined them from just running them until It primed.

 

[Seven Gables]

Been so long I can’t remember for sure but I think I always greased the cups before installing also

 

[r8f1k]

I’d think if ordered them for your model pump and supplier knew the cylinder diameter they’d of sent the correct ones.
Been 30 plus years since I put a set of cups in my old FMC but I do remember when new they were a little larger than the bore of cylinders. That’s why I softened them in boiling water, still had to drive them in with the special tool and hammer.
Are you having trouble getting and holding pressure? When you put the new ones in we’re they real snug fit like I described?
I’m 99% sure you haven’t ruined them from just running them until It primed.

The new units are exactly 2". They are in there snug, but not super tight. My concern is that they leak a little BEHIND the cylinder head and onto the ground. Water is getting around the piston cups in some way or another. Hence my question on putting in units a little larger than the cylinder bore. They definitely did not need to be heated up or pounded in place. I was able to get them sized by a guy who serviced hydraulic equipment and these units just happened to be 'laying around'.....no real stock of a variety. Dumb luck really.

 

[Seven Gables]

Just by your description of how they went in I’d have to say the cups are little too small, kinda tough call though. Going by memory I’d describe putting the new ones in my FMC as very tight, definitely had to whack that pipe tool with a small 2-3lb sledgehammer pretty good.
I’d call a reputable Myers pump supplier and tell them what your situation is , they should be able to tell you exactly what size the cups should be for your model.

 

[r8f1k]

Just curious, were you guys able to see the video of the control panel?

 

[Seven Gables]

Yeah I could

 

[old and tired]

no problem seeing video. Why did you put blue at the top, when sequentially it should have been after the orange? or do the lights indicate where on the fan the nozzles are set at?

 

[r8f1k]

no problem seeing video. Why did you put blue at the top, when sequentially it should have been after the orange? or do the lights indicate where on the fan the nozzles are set at?

So each light represents a nozzle and the least used nozzles are going to be the upper most (blue) nozzles. Very few of my trees have any canopy at that high of a degree above the sprayer, so I made it the last selection of the panel.

 

[r8f1k]

As I have explored the internet for more piston cups, I have found that there are many available in China. I am not keen on buying Communist made good, but they also offer matching cylinder sleeves to go with the piston cups. My thought would be to get an outside dimension of my cylinder sleeves and then try to order some replacement sleeves and cups. It seems that 2.25" is a very common size, so not too much larger than my unit. I could pull the head off this coming fall and take it to a machine shop if I can't pull the sleeves out myself or resize them. I do have a good lathe, a mill and a press, but I don't think that I could mill the inside of the head to oversize it for a different cylinder. I don't really want to turn down cylinder sleeves either to make them thinner, so I would probably have to outsource that labor. Pressing in new sleeves shouldn't be too bad, keeping the depth correct is about the only thing that seems to really matter. My long term thought would be to get this up and running with a slightly upgraded pump and then have an inventory of piston cups to keep it running.

 

[r8f1k]

Ok, so I was able to source a set of NOS Myers piston cups. They are a whopping $92 a piece. I was able to get the OD dimensions of the original units which is 2-3/16”. That seems to track with them being a little tighter than they currently are and how much they have potentially worn. The units from abroad are 2.25” making the difference between them, .0625”. I am betting that I can mount the cups in there “mounts” and shave off .0625 on my lathe to make them 2-3/16”. Thoughts?

 

[airbiscuit]

Could you post a pic of these piston cups? Alternatively, could you sand off 1/16" off those piston cups?

 

[airbiscuit]

 

[r8f1k]

These are mine

 

[r8f1k]

Could you post a pic of these piston cups? Alternatively, could you sand off 1/16" off those piston cups?

Here is a photo of the units from overseas. There are 2.352" so my math is a little off from my previous post. The amount that would need to be removed is 0.1645", a little more than 1/16", but not by much. Sanding the cups could be a good way to go about it, but is there also a way to make/keep them smooth?

 

[r8f1k]

This looks good for leather, but the rubber on these piston cups is pretty thick

 

[airbiscuit]

Are the imported cups cheap enough you could experiment with one on reducing the diameter on your lathe?

 

[Seven Gables]

It looks to me like the cheap overseas cups have a thinner wall than the correct OEM cups to begin with. The other issue it looks like the internal diameter of the Chinese cup is bigger than the correct OEM cup. I think its important that the securing nut fits the inside diameter of the cups to give support to the cup walls. I think you’d be back to where you are now with a leaking pump.
I’d buy the OEM cups and be done with it. It’s not like you’re going to be changing them out once a season, with proper care they should last you many years especially since you’re only spraying 6 acres few times a year.

 

[r8f1k]

Are the imported cups cheap enough you could experiment with one on reducing the diameter on your lathe?

$2.90 each

 

[r8f1k]

It looks to me like the cheap overseas cups have a thinner wall than the correct OEM cups to begin with. The other issue it looks like the internal diameter of the Chinese cup is bigger than the correct OEM cup. I think its important that the securing nut fits the inside diameter of the cups to give support to the cup walls. I think you’d be back to where you are now with a leaking pump.
I’d buy the OEM cups and be done with it. It’s not like you’re going to be changing them out once a season, with proper care they should last you many years especially since you’re only spraying 6 acres few times a year.

Given the price point of the overseas units, I am probably going to buy both. I would experiment with the overseas units to see where it gets me. I would also make an offer on the NOS units. Let's see what happens!