Valve Operation; Illustration 2.G.1: Tong Rotation Control Valve - Farr HD8625 Technical Manual

s & o
eTup peraTion
Ensure adequate lube oil and hydraulic oil levels before starting engine. Use start up procedures as recommended by the power unit
engine operator's manual. Open the Bypass Valve on the hydraulic system, and inspect all pressure and return line hose connections
to ensure correct and secure installation.
IMPROPERLY SECURED HYDRAULIC CONNECTIONS WILL INTERRUPT HYDRAULIC FLUID FLOW, AND
COULD RESULT IN THE FOLLOWING FAILURES:
• A restriction in the pressure supply hose will result in high pressure within the power unit hydraulic system, which
will activate the hydraulic governor and increase the engine speed to as high as maximum RPM.
• A restriction in the return line will result in high pressure within the power unit and the tong hydraulic system, caus-
ing engine speeds as high as maximum RPM, and possible failure of the motor seal.
Following inspection of the hoses, start the engine and allow it to idle until warm. Allow hydraulic fluid to circulate for approximately 10
minutes, then slowly close the Bypass Valve to allow hydraulic fluid to circulate through the hoses and to the tong (circulating pres-
sure should not exceed 200 psi). Place the tong gear shifter in low gear and rotate the tong slowly forward and then reverse with the
throttle valve control lever. Once this has been done and the proper size jaws have been installed, the tong is then ready to run pipe.
2.

Valve Operation

4-way proportional valves control operation of hydraulic devices on the tong assembly such as hydraulic motors and cylinders. When
any one valve is "centered" or in the detent position, there is no hydraulic output from the valve. When the valve is pushed forward
there is an effect, and when the valve is pulled back, there is an opposite effect. These valves feature proportional control, which
means that further extension of the valve handle (thereby further opening the valve orifice) results in proportionally higher hydraulic
output to the controlled device.
The following illustration demonstrates the type and effect of the hydraulic valves with which this tong is may be equipped.
TONG MOTOR
This is a proportional valve. Pushing the valve handle forward will cause the tong motor to rotate in a clockwise direction (as seen
from the top of the tong). This is the desired direction of rotation for making up a joint. Pulling the valve handle in the opposite direc-
tion results in counter-clockwise rotation, which is the desired direction of rotation for breaking out a joint.
I 2.g.1: t r
llustratIon ong
C v
otatIon ontrol alve
hD8625 8- " 35K T
5
/
ong
8
T M
echnical anual 2.15