Hi All,

Even though I've worked on literally thousands of player pianos and 
read every service manual I could get my hands on, I have never yet 
come up with or read an accurately descriptive explanation of how to 
adjust the forward roll or rewind friction brakes. 

The question is: How Tight Is Just Right?

One would think that this should be a measurable amount of drag. 
And, if so, simply attaching a spring scale (like a fish scale) to the 
end tab and pulling on the roll would render a certain figure. However, 
if such a figure exists, I've never seen it. So, I adjust it by "feel". 

How does one explain "feel"? Regardless of which words are used, 
they are all subjective. "Light", "Medium", "Firm", "Slight", and 
"Heavy" mean different things to each person.

The problem with adjusting the forward roll friction brake by feel is 
the effect it has on the air motor. The amount of drag presented by 
the forward roll friction brake has a direct effect on speed of the motor. 
It also has a direct effect on the longevity of the bellows cloth, the 
felt bearings, and (to a slight degree) wear on the chain and the 
transmission. Point in fact, the tempo adjustment, air-motor governor 
adjustment and forward roll brake adjustment are interactive. Change 
any of the three and it has an effect on the other two. This is one fact 
that I have never read about in any service manual or book. 

One has to wonder how the forward roll friction brake was adjusted at 
the factory when the mechanism was assembled. Most friction brakes 
are extremely simple devices consisting of a block of wood, a piece 
of felt, and a flat piece of spring steel. Adjusting the tension is usually 
accomplished by bending the tab (where the spring mounts to the block) 
one way or the other. Other brakes systems employ a bolt and a lock 
nut which allows the tension (or drag) to be adjusted across a wide range 
of settings from minimal to excessive. Still others employ a relatively long 
coil spring that is adjusted by stretching the spring to a certain tension 
and then sticking a small nail through a hole in a block of wood through 
which the spring passes. The point is, in virtually every instance, the 
manufacturer provided some way to adjust the forward roll brake and rewind 
brake. And, that being the case, it seems to me that every manufacture 
was remiss in providing detailed information about how to correctly adjust 
the brakes.

At this late date, can a correct figure for 'drag' be determined? In this 
forum, could we arrive at an acceptable average through experimentation? 

My Lauter-Humana is one of those systems that employs a bolt and a lock 
nut. I have never changed that adjustment. However, its accuracy is 
dependent of the thickness of the felt piece between the spring and the 
brake drum, and I have changed the felt (which was contaminated with 
oil and showed signs of wear). Naturally, I tried to replace the felt piece 
with one that seemed identical to the original piece, but would a few 
thousandths of an inch in one direction or another make a difference? I 
think so.....

My Ampico has two different types of brakes. The forward roll brake 
consists of a block of wood with a felt pad, a coil spring, and a regulating 
screw (like those used to regulate let-off), and it is adjustable via a leather 
nut on the regulating screw. The rewind brake is nothing more than 
a piece of (what looks like) piano wire with a regulating button attached 
to the end. It's connected to the Play/Rewing lever such that when the 
transmission is in the Rewind position, the button makes contact with a 
pot metal disk that's attached via a rod to the Take-Up spool. However, 
both are obviously adjustable!

I suppose the bottomline question is; Does it really make that much of 
a difference as long as it works?

Obviously, there are those who have experienced problems which can 
be directly attributed to a faulty or maladjusted friction brake. And, as 
was explained earlier in this posting, the friction brake is an interactive 
adjustment. At this point in time, and in the absence of factual data, I 
will continue to adjust the brakes by "feel". My approach for many years 
has been to adjust the brake so that the roll doesn't billow. However, I will 
try to remember to carry a spring scale with me and measure the drag on 
various players. Hopefully, over time, I will collect enough data to arrive at 
some reasonable conclusion concerning 'How Tight Is Just Right'.

Musically,

John A Tuttle
Player-Care.com
Brick, NJ, USA