In between reading about the Bezzera Strega in Google translated german and other things I have been thinking of an aspect of commercial lever machines that I do not think has been discussed, if that is possible....namely ergonomics and what this means in a historical context.
I have been drawn to the open group vintage machines for a number of reasons, including just the damn cool look...the bright shiny objects that they are, but all out front of the back panel....a group that you can massage, caress....be somewhat intimate with in a technical way of course. And one commonality is the position of the lever when pulling a shot....much is made of the wear and tear on the barista in a busy shop with a lever machine but I have found that there is a specific body movement when pulling a shot. The grip of the lever should be at height so that the arm makes about a 45 degree angle and one then leans back a bit for the first part of the movement and while leaning back, pulls the lever with a combination of shoulder, elbow and wrist. If the machine and therefore the grip is too low there is way too much elbow wear and actual lower back involvement...it is an awkward and wearing series of muscle movements, mainly on the elbow as instead of pulling straight one has to throw the elbow out to the side and this lateral elbow strain can actually be painful, even in the short term, depending on the strength of the spring , but it does not take long to wear on one with a big lever on a short counter.
And recently I have been working on some machines with a big cantilever front....Astoria and La San Marco, Rancilio and La Cimbali as well but I have not been working on these....and in this design there is no group caressing and the water level gauge is impossible to see and steaming is at about knee level if the machine is placed on a normal height kitchen counter. The pull is off and awkward et al. But with the grip at arms length the controls of the work place are all in the right area for a nice ergonomic lock, pull and steam. This placement also removes even the remote possibility of slipping the grip and knocking most of your teeth out as your teeth are so far away from the action that is is out of even remote possibility.
So it occurred to me that there has not only been an evolution of machine design but also of counter height and overall approach to an espresso bar or cafe. A lever machine had to be HIGH for the barista to comfortably and efficiently operate it and so it had to sit on a high counter....too high for a customer to stand at, therefore the machine was on the back bar or the side.
So when the pump machines came along, first having an E61 group grafted onto an lever body, the machines stayed the same until they suddenly collapsed and allowed the barista to not have the machine up so high and the machine moved to the front counter from the back, and the counter became lower.
But it all goes back to the height of that lever grip.

Amen.

That's actually a very interesting point, especially since I made myself a small coffee bar that's 110cm (43") high. I'm a pretty long guy (195cm or 6'5"), and as far as lever pulling on La Peppina goes, it's pretty ideal, although La Peppina's lever demands a lot of wrist movement.

Grinder height is an interesting factor in this too. I've always wondered why my grinder is about 5 cm higher than it needs to be (saw that when taking it apart). Now I guess ergonomics are probably the reason.

After reading Doug's post, I went back to look at my photo album taken from Naples coffee bars. All machine are on somewhat 42" bar. I also noticed that the pivot point of the lever is always slightly above the shoulder of the barista. I think this make one comfortable pull and when the lever is down, the handle will be around the shoulder, so the wrist and hand will be in a comfortable position.

Thank you Doug for this nice observation.

Interesting post. My bench the 3 grp sits on is 36" high which is a touch short for me at 6'2" but for a few of the girls that work for me that are 5'2-4" it is still a bit of stretch until they get into the slight outward lean. So just consider who else might be using your machine before setting bench height.

Makes sense to me Doug. As you know, I'm currently grappling with the machine height issue. Getting the ergonomics right with my 6'5" height and having to be able to move the machine on and off the stand is my current conundrum. Check out our lever hero "al primo assalto Rosario". The levers are well above his head:

http://www.youtube.com/watch?v=dXJc2bzVX3I

Man, I love that espresso bar.

that clip is epic
thanks to Carlo of Caffe Salimbene who shot this.

I also visited a bar that equipped with 3 groups VBM Pistone sitting on a 42" bench. I tried pulling the levers and it felt so easy, even with double spring inside. I am 5'10" though.