20-02245 REV E
2
GENERAL DESCRIPTION
The model PT-25(FB)-24VDC-RS-485 Pan and Tilt and the R-25(FB)-24VDC-RS-485
rotator are designed to remotely orient underwater, or in-air, TV and photographic
cameras, lights, acoustic equipment, and other instrumentation. It is designed to handle
moderate to heavy payloads. Please refer to the torque curves in this manual for
torque/speed data.
The housing, end plates, and all machined internal components of the positioners are
made of 6061-T6 aluminum, which is hard anodized for corrosion protection. The units
are also optionally available with stainless steel or titanium housings for applications in
highly corrosive environments. Other external hardware such as screws and retaining
rings are made of stainless steel.
The drive train for the positioners use reversible brushless stepper motors coupled to
the output shaft through low backlash harmonic gear assemblies. The output gear of
the harmonic reducer is bolted directly to the output shaft. The output shaft is supported
by stainless steel ball bearings.
The motor drive technology used in the positioners is that of a unipolar stepper. Motor
rotation on the positioner is controlled by a small Printed Circuit Assembly (PCA)
mounted to the shaft plate. The circuit board receives the +24VDC (nominal) input
voltage from an external remote Controller and generates the step sequence necessary
to drive the stepper motor.
To operate the positioner, the user can send either a rotate command or an absolute
position command. The unit has a range of speeds available for rotation. Position
commands can be sent within a 0-360 degree range. Position moves are done
according to a speed profile which has adjustable acceleration/deceleration, maximum
velocity, and braking. In braking mode, a current is maintained through a winding of the
motor in order to prevent the output drive shaft from moving due to external mechanical
loads.
An additional safety feature of the positioner is slip/stall detection. If an axis stalls
during acceleration or slips due to an overly heavy load, the axis will detect and brake at
the last commanded braking value.
If the positioner is oil-filled, the pressure housing shall be compensated by use of a
Bellofram. This provides a slight positive internal pressure to minimize shaft seal drag
and potential leakage problems due to hydrostatic pressure. The oil serves to provide
continuous lubrication as well as cooling to the internal components.
Electrical connection is made through an underwater mateable connector (LPMBH-4-
MP). This connector has a right-angle configuration to minimize the swept-out volume
requirements of the positioner.
