Vinten Vision 250 Specifications download pdf (Page 27)

TF drag

Vinten’s TF (thin film drag) is a true fluid

drag in the purest terms. Utilising the unique

p

roperties of a proprietary fluid TF drag

provides smooth predictable resistance over

a wide variety of levels and temperatures.

TF drags are constructed of multiple

rotating plates alternating with static plates

surrounded in the fluid which is vacuum filled

to eliminate all air from the drag. The plates

do not contact each other but are separated

only by a thin film of the special fluid. When the

head is moved the rotating plates move relative

to the static plates creating a velocity profile

shearing the fluid leading to drag (fig 1.0).

Drag level is infinitely adjustable by varying

the area of overlap between the static and

rotating plates.

At low to moderate speeds the fluid is in

laminar flow and the separation of the plates

(h) is constant yielding an evenly increasing

level of drag with fluid velocity (u). As the pan

(or tilt) motion speed crosses into the “whip

pan” region the flow of fluid between the static

and moving plates becomes sufficiently fast

for the Bernoulli Effect to reduce the fluid

pressure between the plates drawing them

together the coefficient of lubricated friction

of the plates is equal to the fluid drag at this

speed but does not increase as motion speed

increases. This results in a smooth transition

t

o almost constant drag force regardless of

velocity (above the threshold) and the perfect

whip pan.

As soon as the motion speed is reduced below

the level required for the plates to be deflected

the fluid returns to the void between the plates

and normal fluid drag is restored.

Vinten’s Thin Film (TF) Drag Technology

Vinten patented TF drag

system is designed to offer

complete control at any level

of movement, allowing you

to concentrate on achieving

the best possible filming. The

high levels of control allow you

work without compromise

delivering smooth movement

is any situation.

• Continuous, infinite drag adjustment

control

allows you work without compromise

delivering smooth movement in any situation

• An extensive range of drag from

exceptionally light to exceptionally heavy

allowing the camera to work in tune with you

• A wide operating temperature range

from -40°C to +60°C means you can use

the pan and tilt heads in a wide range

of environments with uncompromising

performance guaranteed

• Outstanding whip pan control

Studio/OB Pan and Tilt Heads

TF Drag Technology

Area

Velocity

Force

Height

drag force = area

*

viscosity

*

( )

velocity

height

moving plate u = u

fixed plate u = 0

max

Height

Fig 1.1

u(y)

Fig 1.0

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