Berliner Pumpen - a 2nd valve variant by Adolphe Sax
Posted: Tue Feb 24, 2009 4:48 am
In another thread I wrote this on the Berliner Pumpen valve system:
Klaus
Already early makers were aware of the problems arisen from having the short 2nd valve loop exit and re-enter on either side of the piston casing. In a pre-1871 Eb altohorn Adolphe Sax off-set the through-airpath in the 2nd Pumpe/piston, so that the geometry of the airpath of the engaged 2nd valve became very similar to the one seen in modern rotary valves. I just came by some photos to be relayed here.Re: Early tuba orchestral parts
by imperialbari » Tue Aug 26, 2008 5:00 pm
windshieldbug wrote:
tubashaman wrote:
Also, I think it is ironic that the Moritz tuba is 5 PISTON valves, and currently Germany uses ONLY rotors
The Moritz (and similar tubas) made use of the Berlinner piston, whose closest relative is the rotary valve, and not the Perinet-type piston valve...
The bug is true, but for those wanting to google further on the topic the precise spelling and term may be of good use: Berliner Pumpen.
I have a defunct V. Scmidt of Copenhagen F tuba with 3+2 BP, where it is interesting that the 2 left hand BP sit first in the airpath and have the function of our first two valves on modern tubas.
The top layer passages in the Pumpe (piston) are very similar to the passages of an activated rotor, only offset 45°, as the exit and re-entry into the valve casing sit perpendicular to the direction of the main bugle trough the valve block. This is one of the weak spots of the system, as it can only be applied to instruments large enough to allow the 2nd valve tubing pass below the bottom of the casing and come back up the other side. Never saw anything smaller than a baritone or a valve trombone with these valves. The strong side is the un-disturbed 90° turn to/from the valve branches where the rotors have combined turns of 180° just to enter a valve loop.
The bottom layer passage is even better, as it goes right through the BP, when it is not activated.
I am very interested in the geometry of valve passages, and I wondered, why the Berliner Pumpen went out of fashioned, but only until Sven Bring of Stockholm and Søren Roi Midtgaard of Aarhus/Billund (both members of TubeNet) started providing me photo material. As for passage geometry the BP are unsurpassed. But they have to be fat (= large diameter). And the 2nd valve loop passing around the end of the casing forces the casings and the moving Pumpen/pistons to be short. The longer Perinet pistons are pretty well steered directionally in their movements. The BP are more prone to wiggling thereby causing much more wear on the casing. The system is too vulnerable.
As I see it, the spirit of the BP today is best represented by what I call the American low brass front action block. The valve type is Perinet by technology, but the airpaths of valves ##1, 3, and 4 have exits and re-entries into the pistons at even smoother angles than 90° (actually 135°). Only the second valve is compromised to avoid the around-the-piston-casing wrap.
I like the airpaths of the Berliner Pumpen and also of the Wiener Pumpen. But like a modern system with a next to ideal airpath (the Thayer valve) these old systems are clumsy and vulnerable. The rotors won the original race in the German, Nordic, and Slavonic speaking areas, whereas the Perinet pistons won in the French and English speaking areas. Today we see a few more systems, where one might say that the Hagmann is a Perinet type airpath put into a rotor, and the Willson Rotax(?) is a rotating Berliner Pumpe.
Klaus