Cylinder Hand Question - Philosophy

[Sparks]

A question on the design of the S&W hand, please. As the hand rises, the cylinder rotates until it carries up. The hand rises until the hammer is cocked (single action) or until the hammer falls (in double action). To insure that the cylinder actually locks into position, sufficient extra movement of the hand is necessary. After carry-up, what is the hand designed to do during that extra upward travel? Is it designed to be pushed backwards to skip over the ratchet pad, or pushed outward to move around the ratchet pad? And in either case, how is that motion achieved without causing a hitch in the trigger pull?

It is interesting to note the complex geometric shape of the individual ratchets and compare them with their simpler counterparts on the early Single Action revolvers. In the latter case, a 2-tier hand was used to achieve sufficient cylinder rotation. But naturally the hand was operated by the hammer, and did not affect the trigger pull.

Thanks,
Sparks

 

[Hapworth]

That hand rotates the cylinder into lock-up with the cylinder stop by "pushing" upward against one edge of the ratchet tooth. As the tooth rises it rotates counterclockwise and out of touch with the hand; the hand simply continues upward alongside the rotating tooth's outer edge as the tooth "banks left" and into lockup.

 

[WR Moore]

Actually, the ratchet never loses touch with the hand. The hand tip does rotate the cylinder as it rises. As the cylinder reaches alignment with the barrel (ranges), the side of the hand bears against the ratchet lug to hold the cylinder in alignment. All this is intended to happen before the hammer falls in either single or double action.

In the S&W system, errors in carryup/ranging are solved by the fitting of a thicker hand, not a longer one.

 

[Sparks]

That hand rotates the cylinder into lock-up with the cylinder stop by "pushing" upward against one edge of the ratchet tooth.

That much is clear and is easily visualized. You have stated the purpose of the hand.

As the tooth rises it rotates counterclockwise and out of touch with the hand

No sir, the ratchet pad can not move out of touch with the hand because a very slight misalignment or slight tolerance error would result in no carrry-up.

the hand simply continues upward alongside the rotating tooth's outer edge as the tooth "banks left" and into lockup.

This situation holds true in a worn or mis-adjusted gun that is cocked briskly. The momentum of the cylinder can, by itself, carry the cylinder all the way into lockup (battery, carry-up, etc). However, I would immediately place a red tag on this gun saying "Unsafe to Fire". I was inquiring about the part of the hand operation AFTER the cylinder carries up.

Sparks

 

[Sparks]

As the cylinder reaches alignment with the barrel (ranges), the side of the hand bears against the ratchet lug to hold the cylinder in alignment.

Thank you. This movement makes the most sense to me. Once the cylinder is locked in position, the ratchet pad stops moving. Yet, the hand continues to move in the majority of DA revolvers today. My opinion is that this extra upward movement is an excellent idea because machining tolerances will cause the cylinder to carry up at slightly different points on each chamber. The hand must rotate the cylinder into lockup BEFORE it completes its upward motion to assure that each chamber will carry up. It seems most likely to me (as you stated) that the hand is forced outward slightly, causing the left (inner) face of the hand to bypass the locked ratchet pad.

In single actions a revolver is thought to be perfectly timed if the cylinder carries up just as the sear falls into engagement. Since a 2-tier hand is used, the hand does not need to bypass the ratchets. The movement of the hand is tied directly to the movement of the hammer, unlike the S&W hand which is connected to the trigger.

Thanks for considering my questions.
Sparks

 

[Hapworth]

Actually, the ratchet never loses touch with the hand. The hand tip does rotate the cylinder as it rises. As the cylinder reaches alignment with the barrel (ranges), the side of the hand bears against the ratchet lug to hold the cylinder in alignment. All this is intended to happen before the hammer falls in either single or double action.

In the S&W system, errors in carryup/ranging are solved by the fitting of a thicker hand, not a longer one.

My word choice was imprecise. What I was trying to convey was the changing position the hand undergoes in relation to the ratchet tooth as the cylinder rotates; once carry up has occurred the hand's initial and primary point of contact -- the tip -- is no longer in the direct touch with the tooth as it had been when pushing upward, but instead, due to rotation, the hand's left edge instead rests alongside the tooth.

And although that final hand position before reset occurs does aid in alignment, isn't the cylinder stop the primary aligning force between chamber and forcing cone?

 

[Hapworth]

No sir, the ratchet pad can not move out of touch with the hand because a very slight misalignment or slight tolerance error would result in no carrry-up.

Indeed, correct idea but poor word choice on my part; see my reply to WR Moore above.

This situation holds true in a worn or mis-adjusted gun that is cocked briskly. The momentum of the cylinder can, by itself, carry the cylinder all the way into lockup (battery, carry-up, etc). However, I would immediately place a red tag on this gun saying "Unsafe to Fire". I was inquiring about the part of the hand operation AFTER the cylinder carries up.

Not quite. The hand does indeed continue upward alongside the rotating tooth's edge as the tooth rounds into lockup; once the cylinder stop engages and lock up occurs, there's an additional thousandth or two upward motion of the hand before apex, aligned alongside the ratchet tooth.

That's correct carry up, not worn of misadjusted.

 

[tomcatt51]

A too thick hand gives the "glitch" at the end of your DA pull "expert" gunwriters love to call a "staged" trigger.

"Just right" gives no "glitch" and a cylinder that locks just as the hammer releases in DA.

 

[Sparks]

My word choice was imprecise. What I was trying to convey was the changing position the hand undergoes in relation to the ratchet tooth as the cylinder rotates;

Yes, and that is exactly my original question. I believe that this motion is not widely understood.

although that final hand position before reset occurs does aid in alignment, isn't the cylinder stop the primary aligning force between chamber and forcing cone?

Of course the cylinder stop or bolt is what sets the registration between cylinder and barrel. The hand does not align anything, or hold anything in place. It is responsible for rotating the cylinder far enough for the bolt to fall into the cylinder's locking groove. Since the amount of required cylinder rotation differs from chamber to chamber by a tiny amount, the hand must have enough extra travel to compensate for machining tolerance errors. It is the hand's movement during that "extra travel" that I was inquiring about.
And it seems that the hand is forced to travel around the outside of the ratchet pad during that time. Anyway, an interesting detail in revolver operation.
Thanks again,
Sparks

 

[2152hq]

The hand shouldn't have to move to the side to slide by any of the ratchet teeth when the cylinder is locked in position.
Yes, machining of the parts, especially on older mfg revolvers left tolerances that were not as tidy as they can be today.
One ratchet tooth could and usually would be a few .0000" wider than another. The hand is a single flat part and more easily controled in thickness in mfg and fitting.
It was(is?) in the final fitting that the ratchet teeth are individually cut on the side that bears against the hand if needed. It's done w/a file.

That's to ensure that the hand slides by each ratchet in operation w/no slack (slow timing) and no jamming or interference (the hitch or hard spot at the end of the cocking cycle felt sometimes on individual chambers.).

If needed, a wider hand, wider by a .000 or 2 is put in place to take up a slow timed chamber and then the other ratchets may need a very slight trimming each to remove any hitch from the over size hand.

There should be no side to side play in the hand if it's fitted up right.
It doesn't effect trigger pull if fitted correctly as there is no engagement of the hand with anything after the cylinder is pushed into and locked in position. No resisitance from it's final movement as the trigger is pulled. It's just sliding along side of the ratchet tooth.

On the Colt, it's completely different. The hand has 2 teeth. The upper engages on ratchet and pushes the cylinder part way around in the rotation, then disengages. At that time the lower tooth engages the next ratchet on the cylinder and brings the cylinder into full allaignment.
Out of time Colt problems are mostly the lower tooth of the hand being worn or short. That's why peening the hand can work (sometimes). This is the same for the SAA or the old style Colt DA's

The longer hammer swing on the Colt DA complicates correct timing and makes for the often accepted cylinder rolling into locking position as the hammer drops. It's not in time,but many accept it as so.

It's difficult to get the SA and the DA on a Colt to time correctly with the hand connected to the trigger,,the hand designed to press against the ratchet tooth at the point of the bolt dropping,,,and yet the trigger has to be pulled a tiny bit further in DA than SA to discharge the gun.

 

[ViperR]

Actually, the ratchet never loses touch with the hand. The hand tip does rotate the cylinder as it rises. As the cylinder reaches alignment with the barrel (ranges), the side of the hand bears against the ratchet lug to hold the cylinder in alignment. All this is intended to happen before the hammer falls in either single or double action.

In the S&W system, errors in carryup/ranging are solved by the fitting of a thicker hand, not a longer one.

Exactly! And clearly stated in laymans terms. There are always misconceptions thinking it is the length that matters (just ask my girlfriend).
I have a diagram on the rachet/hand relation that would be a good visual. I just have to find it in my pictures somewhere.

 

[WR Moore]

Belated answer to the cylinder stop: the primary purpose is to prevent over rotation of the cylinder and also alignment (range) of cylinder and barrel bore.

 

[dant]

must remember that the 'thickness' does indeed matter, they used to come in various thicknesses in and around the .095-.099 " as an example in the 'K-L frames..s well as the proper fitting of the 'tip' and the slant ( plus a break in the edge of the inside to NOT chew up the ratchets in question)..........yes the hand does affect ( do ) other things when taking into consideration the window slot of the frame , in relationship to the 'adjoining/corresponding' ratchet ,there is a "nominal " distance in there.....been MANY years since we had looked at some of the 'old'patent drawings.............

I can remember way back in service repairs when you could put a slight bend in an undersized hand to make it work.............