O'Connor Model 30 Fluid Head
photos by John Beale  April 17-25 2007  bealecorner.com

These images show partial disassembly views of an O'Connor Model 30 fluid head. It was purchased used on Ebay in 2007 and is of uncertain age; possibly from the 1970s or earlier. The tilt shaft is supported on one side by the fluid tilt bearing, and on the opposite side by the counterbalance spring assembly. There are two coaxial pairs of counterbalance springs, mounted between two plates. The top spring plate moves down and compresses both pairs of springs as the head tilts off level. The top plate has an eccentric mount to the tilt shaft, so that spring compression and tilt restoring force are sinusoidal. The bottom spring plate moves up as the spring adjust bolt at right is turned clockwise. This increases the restoring force for a given tilt angle, allowing the head to balance a heavier camera. The fluid-drag action is provided by the fluid shear between a rotating steel cylinder and a surrounding adjustable-diameter plastic sleeve, shown in this photo. In operation the pan and tilt bearing areas are filled with a very thick silicone fluid.

When I got it, the head was filled with a very thick sticky grey material. I have heard that the original O'Connor fluid was clear, so I have no idea of the history of this particular head, or what the grey goo I found in it really was. The total fluid volume is approximately 4 fluid oz. (120 ml). I cleaned out the grey goop and replaced it with a clear polydimethylsiloxane called Dow Corning 200 fluid in the 100,000 centistoke (cSt) viscosity, which is really quite viscous but not as thick as what came in the head. I believe the minimum order from Dow Corning is 50 pounds (!) but companies can get a free 500 ml sample, which is more than enough for this purpose.

I am satisfied with the resulting pan and tilt action of my re-filled head. The drag adjustments go from loose to "moderate" drag. I would guess some might want a more viscous fluid to achieve greater drag, such as the 300k cst viscosity. If the Dow Corning fluid is not easily available I don't know of good alternatives; Cargille Type OVH immersion oil is sold in small quantities but is lower viscosity, at 46000 cSt.  By the way, O'Connor will sell you a #30 head fluid refill directly for about $90, and they can refurbish your used Model 30 head for $1100. (Prices as of April 2007)

In case you are thinking of doing this yourself, here are a few more notes:

1) There's no service manual for this head I know of.  I asked O'Connor about it on the phone, and they said there never had been one.
2) I spent about two months looking for replacement fluid. 
3) If you clean out & replace the fluid, plan on spending a full weekend at least on it.  Cleaning the gunk off all the parts was very time consuming, and there's no solvent I could find that had much effect (I tried at different points water, soapy water, isopropyl alcohol, mineral spirits, and acetone). Gojo orange pumice hand cleaner did help get it off my hands.
4) My #30 head had no gaskets on the access plates, at least no recognizable ones. During reassembly I used a thin bead of "shoe goo" to seal all auound the edges of the plate, another somewhat fiddly process.  If you don't have the o-ring around the rotating bottom part pressed in and fully seated all the way around, it will slowly leak fluid out from the base. Even some factory-original models of this head were known to leak fluid over time.

 location of bottom o-ring

Just for reference, this model was apparently first released in 1976. 

"The New O'Connor Model 30 Fluid Camera Head"

Introduced at Photokina 76 was the newest addition to the O'Connor line -the Model 30, which the manufacturer considers to be the culmination of its quarter-century of experience in building fluid heads and regards as quite possibly the most desirable head the company has ever built.

It is surprisingly small and weighs only 5 lbs. Yet it will easily handle motion picture and video cameras weighing up to 30 lbs. It has all the features and smooth-steady action found on the largest and most elaborate O'Connor heads.

This entirely new fluid head is unlike all others in its engineering. The counterbalance is unique in that it can be easily adjusted for a 10- to 30-lb. camera while in the field. The continuously adjustable new fluid type drag mechanism is a totally new concept for O'Connor providing very smooth and sensitive panning through 360, and tilting up to 60. Both the pan and tilt locks are independent of the fluid system.

For smaller motion picture and video cameras, the Model 30 is the perfect head for ultra-smooth action photography.


Capacity ........... 30 lbs. (13.6Kg)
Weight ................. 5 lbs. (2Kg)
Size ........ 4-1/4" high, 7" wide, 5" long
Pan ........................... 360
Pan lock ...... Independent from fluid system
Tilt............. 60 up and 60 down
Tilt lock Independent from fluid system
Counterbalance ... Adjustable in field from 10 lb. to 30 lb. camera
Camera mounting screw .... 3/8-16
Base ..... Flat (3/8"-16 threaded insert)
Handle .... Vertically and horizontally adjustable
Temperature range ..... 0 -20 to 120F (-29 to 49C)
Material ............. Cast aluminum
Finish ... Black wrinkle baked enamel, anodized or plated
Bearings ..................... Roller
Shipping weight........ 7 lbs. (3.2 Kg)

from American Cinematographer vol. 57  #12,  December 1976

For reference, the photo at left shows the tilt-drag area of a Bogen / Manfrotto 501 head. Concentric rings or grooves match up with similar grooves on the opposing surface, and are filled with a clear (silicone?) grease. A different, light brown colored grease coats the light-colored outer ring, which may be a teflon surface. This greased-friction type head is not as smooth overall as a "true fluid head".

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