Diff. between 'A' and 'A2' pinspotters?

[jim willing]

Ok, perhaps the most doofus question this week, but I'm primarily an AMF wonk...


So... in the proverbial 25 words or less (yeah, right) what are the primary/major differences between the 'A' series and 'A2' series of Brunswick pinspotters?


...and for free bonus points (and worth every cent) just what does the 'JetBack' conversion (upgrade) encompass?


Thanks;

-jim

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[KL Kevin]

Re: Diff. between 'A' and 'A2' pinspotters?

Sequence of machines (from slow to fast cycle time) A, Jetback, A-2

Primary mechanical differences between A and A2 are in the pit cushion, gearbox triggering mechanism, and lift rods.

With the "A" machine, the machine had to start the cycle (rake powered down by the machine so the cushion could raise up to allow ball to pass through and return. A-2 shotgun mechanism allowed cushion to lift up as soon as ball impact occurred, so ball could go into return mechanism sooner.

A-2 used a powered ball accelerator to propel ball into subway at high speed for better ball return time (to the point where slowdown mechanism is required in the front), A machines use a gravity feed system.

The jetback is essentially a souped-up A, running at a speed between the A and the A2, with the a-2 style cushion and lift rods, and an abominable device known as a ball buster .... errrh ... booster, which provides some acceleration past the gravity feed stage, but not enough to require a retarder up front.

The buster is the one part of my jets that i can honestly say I hate to work on with a PASSION, it was truly something Rube Goldberg would have admired.

Many mechanics found that the A2 was almost TOO fast, and have put jetback pulleys on their motors to slow them down to jetback speed, reducing wear and tear, and making the machine run smoother.

Kevin

[Wookie8662]

Re: Diff. between 'A' and 'A2' pinspotters?

Heya!

Kevin is right about the a/a2's. I have do disagree about the ball boosters. If I ever go to work in another center that has accelerators, I will rip them out and put in boosters. I havent had a booster problem in about 3 years now. Of course, thats after I replaced the old "go-cart" tires with the newer urethane "V" tires.

Then again, every mechanic will have his favorites, and dislikes. I'm not saying Kevin is wrong. Just that I prefer boosters over accelerators.

The fast drop rake, and the pit cushion were MAJOR improvements to orignal machines.

Heh, I still have the cycle solenoids mounted on the detectors here.

Wookie

[GPS]

Re: Diff. between 'A' and 'A2' pinspotters?

Jim, thanks for a great question and to KL and Wookie for their answers. As an AMFer I always wondered too.

[billman]

Re: Diff. between 'A' and 'A2' pinspotters?

Let us not forget the 90 degree over-travel in the Model A. It is used to help "speed up" the cycle of the machine on 2nd ball. It consists of the double cycle cam and rake cam followers and their hardware. They allow the machine to travel past 0 degrees on 2nd ball. P.S. This is why you should NEVER try to lift the holding hook on a model A when it is on 2nd ball!!! Also the reason not to get under the deck when the machine is on the hook!!

billman

[KL Kevin]

Re: Diff. between 'A' and 'A2' pinspotters?

Wookie:

My point about the boosters is that they're a PITA to work ON when they break. At risk of getting flamed for "m-i-c ...", I cut a pair of slots in the bottom of the steel frames when they're out being re-built, so when that lovely bearing freezes up without warning, drop 6 bolts and a good shot with the johnson bar and she's back to gravity feed in 5 minutes. As far as operation goes, they work well, and none of the crap under the approach to break. But when one goes, it's no fun at all. Never worked on machines with accelerators

Cycle solenoid ... what's that? ... LOL!! Jets at 20,200 serials, with cable triggers and the oil bleeder time delay.

Another note for the amf'rs ... the A-2 used a different deck lowering mechanism called a scotch yoke, which provided a longer dwell time at 270 to spot the pins, as well as a different deck cam, both designed for the higher speed. Best analogy I can give you is a table motor that would run at say ... 17 RPM, with the chassis telling her to coast for an instant when spotting and then power on again. Any other info you want, ask away. Guaranteed there's hundreds of years of experience in this forum.

Kevin

[BT-Jerrid]

Re: Diff. between 'A' and 'A2' pinspotters?

Dont forget about the differences in the way the time delay works, I believe the A's (and I think some A2's) the time delay was adjusted by changing a stem in the housing of the 4:1 which allowed gear oil to pass through an orifice in the stem when the dashpot was lowered. I say maybe some A-2s also because I have some 4:1's on my jap A-2s that have the hole for the stem in them. Where the later model Brunswick machines went to an electronic time delay. BTW Kevin Ive stood in the back isle many nights thinking how nice it would be to have boosters while I was putting accelerator drive belts back on 2 at a time during a plastic ball league.

Jerrid

Re: Diff. between 'A' and 'A2' pinspotters?

"give me boosters or give me death!"

i've worked on both and would take the minor headache of a problem booster over a touchy accelorator that wants to toss belts during state tournys.

only problems i ever encountered w high speed A2 machines were constant rake shaft breakage at the stops and when the bottoms of our brunswick red crown pins would wear out, lots of shaky full settings for 1st ball. ( we had 1961 a machines converted to A2 in 1967)

[Drillmn300]

Re: Diff. between 'A' and 'A2' pinspotters?

I have never worked on boosters but to me accelerators are where it's at. Once you lift the whole unit up with the Zot kit your problems are gone, I have not had a belt come off in over 2 years and I can use belts that would have needed changed after the first year. I even put on some older ones that would slip without the lift kit and they have been on for over a year now.
I will take no problems over the tearout KL is talking about.
As far as the thread goes I can add that Brunswick offered a conversion kit for the A's so a person could upgrade. Mine are field converted so I am assuming Brunswick came in and converted it themselves.
Have Fun!
Drill

[Steve Stafford (JBEES)]

Re: Diff. between 'A' and 'A2' pinspotters?

Jerrid,
Sounds like someone changed some 4:1's in your house and used some A version castings. For the AMF'ers there is a different return track setup between the A's and A-2's. The A version sets the return tracks up at the top of the lift rods and the A-2 sets them down much lower allowing the ball to get a boost in speed by dropping the ball at the lift rods down to the return track..this gets an immediate increase in return speed instead of waiting for the ball to get to the comman track and to head up front. Just another small dfference between the machines...

Just my two cents worth...

Steve

Re: Diff. between 'A' and 'A2' pinspotters?

I saw that on the Model A pinsetter that they have 2 of these greased tubes...i don't know what they are called. I know on the A2 pinsetter that there is only one on the 7-pin side...why is there 2 on the Model A? How do you set the Model A pinsetter to 2nd ball without cycling the machine? There isn't that rod you pull on the A2... =\

ßA

[diamondpins]

Re: Diff. between 'A' and 'A2' pinspotters?

the bar you pull on to change to 2nd ball is connected to the detector just pull on the latch itself on the detector to change to 2nd ball i believe this is called the detector lever assembly

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james

[KL Kevin]

Re: Diff. between 'A' and 'A2' pinspotters?

A2:

Model A machine can be put on second ball by pushing forward on standing pins latch, which is the one on the front 10 pin side of detector. However, if the machine still has the 90 overtravel hooked up, gearbox will engage and run to 90 ... is that what you're saying about cycling the machine??? If so, part of normal operation.

Kevin

[Steve Stafford (JBEES)]

Re: Diff. between 'A' and 'A2' pinspotters?

KL...and if everything is adjusted right, the rake won't go down...LOL

Steve

[bwhite757]

Re: Diff. between 'A' and 'A2' pinspotters?

Alrighty A2,

Model A's, my favorite (to gripe about) I've worked on regular A's, and jet backs, both w/90 degree overs on them. I also currently work on A2's.

Yes, there are two bazookas, as I call them, on the A's, but only one is needed. We took the 7-pin side one off about a year after we put the A's in one of our houses.

To cycle into secone ball. Well that's a little trickie w/90 over's on the A's. If you are just spotting pins and want to clear the deck, I normally just hold down the deck holding hook and reset it. Does the same thing as putting it in second. To get it into second ball after you have spotted the pins, push forward (towards the masking units) the top half of the thing the 10th frame box on A2 hook to. (I don't know what it's called, but it's sticking out of the top of the detector right in the middle, looks like two index fingers pushed together)

You can also push that up to put it into second ball while the machine's at 0, but unfortunantly if it IS misadjusted, the rake will drop when the machine travels 90 degrees.

The thing I've found w/Jets is that they don't move when you put them into second ball, they wait until you reset the machine before they travel 90, meaning the rake tends to stay up 90 after you reset the machine.

Well, that's all I know.
Ciao..


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Brandon White