Can anyone tell me the size and number of balls in the 10hp Stanley crosshead/slidebar arrangement. The channel that the balls run in is presumably a true part circle with a radius same as the balls, rather than a 'V' groove.

The Stanley 1913 catalogue illustrations of a generic engine show a single roller (part no 607-107D for a 10hp engine) above and below each crosshead.

The engine from our car, Stanley 7644, (1914), which is the orignal one, was the same.

I believe the earlier 10hp engines had a ball instead of a roller.

5/8 inch ball running in 5/8 inch groove. One ball to the top, one below i.e. 4 balls
per engine. This is how it is on the dry 20hp engine which is structurally the same as the Model 60 ten hp. I'll post a picture later.

Mike

Thanks for your reply. I am surprised that one roller or ball above and below the crosshead is sufficient. This means that there is not much chance of the piston rod being relieved of vertical stresses since there is a good chance (if not a certainty) that the single point of contact would not be over the gudgeon pin. The crosshead would be trying to pivot,using the ball/roller as a fulcrum to bend the piston rod. But obviously it worked out ok!
Do you think a roller better than a ball? It doesn't matter if a ball twists in its track, but a roller might try to do this and 'gaul' against the sides of its track. Am I seeing faults that don't occur in practice.
Can I assume that the above is balderdash and that your car doesn't show any of these tendencies?
Kind regards
Jack.

Thanks for your reply as well Mike, You confirm Peters reply.
Jack.

Both ball and roller types must cause a bending action on the piston rod but obviously not enough to matter. I suppose the roller type is better at discouraging the wristpin from rocking laterally and this is important if like most of us you are using self-aligning bearings in the big ends - although again the ball type seems to work on my own 20hp engine.

I used ball not roller for originality because I am running a dry engine (with, as you see, an added drip feed). Some (with "wet" engines) now use a rounded section bronze slider which runs in the same grooves but I was doubtful of being able to oil it enough. The roller type has an advantage because you can put a small oil hole in the top groove of the crosshead which lets oil dribble onto the wristpin which is genreally the worst oiled bit of the whole engine. You can't do this with the ball type as the ball bounces over the hole - hence my drip feed.

I am going to try to put a picture in here which should show as a thumbnail on which you click to see it bigger. If this fails I'll put a link to the picture.

Oh well that's what I had to do!!


[photos2.flickr.com]

Mike



Edited 1 times. Last edit at 01/14/05 04:20PM by Mike Clark.

Thank you Mike, a very informative picture. One last question, if you weren't worried about originality would you consider using more than one---maybe 2 or 3 balls each side of the crosshead. Can you see any objection to that?

Regards,
Jack

Jack,

Much of the distortion of the Stanley engine in action is a sort of diagonal racking motion in which the frame rods are twisted so that if you could look at it from the side you would see that what should be square is actually going trapezoidal alternately up and down. This means that however many balls you put in the track the contact points will be top of the back ball and bottom of the front one alternating so little is gained by adding more.

In fact I suspect Stanley used one ball top and bottom just so as to accomodate this flexing. The balls probably float themselves to the optimum spot when it's working although if the crosshead slides are a bit far apart the unloaded ball will be free to rattle about. Come to think of it the balls roll pretty much to the limits of their tracks (where they are stopped by a stud) so it could be that putting an extra ball in would cause collision and a sliding rather than rolling action at the end of the travel. I'll look at my engine tommorrow and repeort back.

Overall I would think Stanley got it right and that the great advantage of balls or rollers (specially in a "dry" engine) is that they are very tolerant of poor oiling.

Mike

Yes I see now Mike, The length of the track in the crosshead governs how many balls. Assuming a ball starts from one end at the beginning of a piston stroke,then it must not quite reach the stop at the end of the stroke or else it will skid when the stop is reached. If however the crosshead is long enough then an extra ball might be possible. I always think that the crosshead looks at its worst when the crank is on front centre and a good portion of the c/head is clear of the front of the slidebar and the single top ball at the back ----it looks like something bad is about to happen! Thought maybe an extra ball might at least make it look better!!
If you have any more thoughts, or have any comments on how much wear you have encountered on the piston rod/back cylinder cover gland bush, I would be interested to hear.
Regards
Jack.

Jack

I've not really done enough miles to wear it out - but after about 2000 miles there is no detectable wear on my hard chromed piston rods. Glands take a turn or so now and again but no indication that anything is going wrong here.

Mike