This is topic Direct drives.... Why? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Jack Ondracek (Member # 1466) on 04-26-2003, 12:09 PM:
 
I understand some manufacturers have machines that have always been driven from the top down... but other than for personal taste (some like Fords, others like Chevys), is there any solid technical reason to specify driving a projector head directly, when given the option?
 

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Posted by Gordon McLeod (Member # 33) on 04-26-2003, 01:13 PM:
 
The only advantage I could see is it eliminates one belt that could be a problem if it goes loose
 

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Posted by Paul G. Thompson (Member # 655) on 04-26-2003, 01:24 PM:
 
Maybe it goes back to the Western Electric days with the old Simplex and WE 211 sound head. If memory serves me correctly, the soundhead had no sprockets. The projector hold-back sprocket was the last sprocket before the take-up.

The Pro-35 could be considered as a driect drive projector, I guess. But the sound head was driven by the projector. That took another belt.

Another reason I see is that gear reduction to the projector is so steep when it is driven by the soundhead. Much more stain on the gear train. If the projector was direct drive like the Pro-35, the soundhead would not present a significant load to the projector.
 

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Posted by Ken McFall (Member # 845) on 04-26-2003, 04:16 PM:
 
It's more to do with the fact that in the 'old' days you could mix and match sound head with picture head.

Western sound head with a Kalee picture head as an example. There were many adaptor plates made to siut almost any combination.

Today projectors are sold as single systems and not separate so the design can reflect the simplest method that suits any given system.

Take a look at a stong projector, JJ for example, and you are looking at an older style where the heads are seperate and therefore need to be linked in some way. Then look at an FP20, Vic 4, 5, 8 any modern system and as single units they are driven by one continuous drive system.

Hope this makes sense...
 

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Posted by Gordon McLeod (Member # 33) on 04-26-2003, 05:46 PM:
 
Actually Ken all north american machines with main exception of the devry and christie were and remain a multi unit system that is a mix and match arrangement
This was true even of the GK's as there were many GK19's mounted over here on other soundheads and the opposite
As for the european machines there soundheads were passive and bolted on the rear of the machine so one could have a ernamann 7 with say a Klangfilm soundhead or a phillips sitting behind it on the base
What I believe Jack was referring to was specifically the cenutry projector soundhead combo that is available in two styles the regular with the motor driveing the soundhead and a second belt driving the projector head or the direct drive with the motor driving the projector directly via a belt and a extension in effect of the verticle shaft extending down into the soundhead
 

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Posted by Ken McFall (Member # 845) on 04-26-2003, 05:58 PM:
 
Thanks for that Gordon.

I'm not familiar with the equipment you mention. Things have changed a lot in recent years.... say the last 20 or so, and generally system are single units... so they are all in effect direct drive as the mech is a single unit. There is still a lot of older equipment in use here, Westar's for example, that are linked by a flexible vertical drive shaft link. Then there are the likes of Kalee where the picture head is driven via the soundhead. The Vic 5 which drives the the projector and lower spocket from a motor belt connected to the top sprocket etc etc.

The only 'real' drirect driven projector I can think of right now.... after a few G & T's, is the FP 20 series where the motor drives the intermittent directly.

I'm not too sure what difference it makes at the end of the day. Bottom line is no wow or flutter from the sound head and a steady constant drive to the picture head. If the mech is run nice and smooth it'll last much longer. How thats achived is not really important.....

I'm sure there will be someone who will tell me I'm wrong.
 

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Posted by Bernard Tonks (Member # 809) on 04-26-2003, 07:31 PM:
 
My Westar projectors sat on RCA 9031 soundheads with direct gear drive. I've seen some combinations in my time on Western Electric Universal bases & RCA soundheads, BTH, Ross, Simplex, Kalee projectors.

Ken, Never did like those Westrex flexible vertical drive couplings. I was let down with them a couple of times at the old Carlton Theatre, Haymarket. The RCA gear drive, never in 25 years.

Hope Brixton is going well for you. I did a days relief at the old Pavilion Pullman in the year dot, when is it was a double feature Cowboy & Indian cinema. Projectors were BTH Supa's MK 2.

I have a relative in Brixton running an African gifts shop.
 

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Posted by Jack Ondracek (Member # 1466) on 04-29-2003, 01:15 AM:
 

quote:

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from Gordon:
What I believe Jack was referring to was specifically the century projector soundhead combo that is available in two styles...

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