Using Theoben pump to re-charge an Eliminator ram.
Has anyone here done this before? I've removed the stock and schrader value sealing screw with o-ring. It appears there might be a plastic sleeve before the valve. I supposed to see screw threads, correct? The chamber before the valve is smooth. Both Theoben pumps and gauge I own all have the same threaded ends.
Further, I haven't seen the maximum BAR these guns operate at online. I know RX rifles are between 23-24 BAR from talking to Beeman 20 years ago. Thank you.
It depends on the vintage of the rifle. The Schrader valve is accessed through the hole, but I don't recall being able to see threads. The pre-HE system can use the original bicycle style pump. Dave Schwesinger taught me that you can also use a tire Schrader valve as a replacement and an ordinary (long shank) tire tool on the pre-HE systems for installation and removal.
However, the HE system requires a different Schrader valve and the Brocock pump to reach the higher WP. The Schrader valve comes as part of the regular seal kit. The HW 90 (IIRC), requires its own pump adapter - so the RXs will too. I use trial and error to get the velocity and smoothness desired.
There is a scuba tank adapter as well. Start off at 600 psi and take it from there.
Tinkered with the eliminator more this a.m. After pointing a flashlight in there I can see the threads. There is another adapter that is smaller (yellow) that fits the port. The gauge fits as well. The black adapter that most people see online must fit other type of Theobens. Apparently there is a technique to this that I have to figure out. Will post what I've learned after ordeal is over.
Do not use the gauge! The HE system uses much higher pressure than the RX system
The procedure that Theoben recommended was to slowly work up to max velocity. My first Eliminator arrived from Litt’s DOA and I received instructions from the factory regarding the charging process.
The adapter is to use the “Slim Jim” pump on both systems.
thanks, perhaps I’m beginning to see the light.
In an exchange w/ JoshIII, in regards to an RX2 (?) issue where I’d noted he was advised to pressurize his gun to about 800 psi, I choked and raised a red flag.
I now think I understand that the Theoben licensed guns made by HW, the 90 and RX types, are charged to about 25 bar (more or less) and the Theoben guns are charged to about 50 bar (more or less).
Is this about right? If not, could you please clarify/correct.
(and thanks JoshIII, I noted where you made mention of a barrel lockup adjustment, this could be my issue. Thnx again!)
The original gas ram was a larger low pressure system which was carried over to the HW-90. The newer HE system has a skinny stem at higher pressure. The only reason for the change was the expiration of the original patent. Theoben created the HE system to get a new patent and touted the new ram as an improvement. IMHO, the opposite is true. The old system is more reliable as it puts less stress on the innards. That is why the HW-90 has proven to be so durable.
A good friend has a 90 in .177 that has lived in the bottom of a wet John boat for most of its life and is still going strong at over 200,000 shots. In 25 years it has only required a new safety and occasional breech seal.
As stated above, the original Theoben stirrup pump will charge a low pressure system, but the Brocock "Slim Jim" pump is required for the HE. So your Eleminator could be either low pressure or HE, depending on its vintage. Just proceed as if it is a low pressure system (slowly) until the desired velocity is obtained I using the slim jim. The hardest shooting Eleminator I have ever had (HE) would launch a 14.3 gr. pellet at 895 fps. But it is harsh and hold sensitive. A more modest velocity is smoother and easier to shoot well.
that pretty much clears up my confusion. I have a RX2 in .177. I too, can be rough on stuff. My ‘Dan lived most of its life as a truck gun.
The barrel on mine seems to “sag” at discharge ever so slightly. I’ve dropped the pressure to about 20-22 bar. I think the “tissue” test might be deceiving in this case. I suspected a smaller piston or cylinder at the higher pressure. I bought the gun used, my 2nd attempt at mastering the magnum .177. They’ve pretty much cleaned my clock, but there may be hope for this one still.
’preciate you making sense out of that for me!
seem to think you’ve been around these parts a very long time.....
(Jerry??? Upstate??? Farms fuel???)
Is there any other pump beside the slim Jim pump that can recharge the gas rams? Something like the Hill pumps. I have a couple of Theoben rifles. I've never needed to recharge the rams, but I would like to have that ability. I believe that both of my rifles have the HE rams. Thanks.
hi Mike, Ive used a foot pump, Hill, FX, most any asian. For my RX, it only took a stroke or two with three being almost too much.
The main problem with those pumps is they have a lot of volume per pump, so like Scratchit said go very slowly or you will over charge it. The Theoben pumps were designed for low volume and high pressure.
Thanks for the info. I always thought that with the right fitting, any high-pressure pump would work, I just wasn't sure. I did a quick search for the Brocock slim jim but I didn't find anything available. Any recommended pumps other than the current PCP hand pumps would be appreciated.