The tractor hydraulic system can operate either a
613B scraper or 613B water distributor. The function of
depending on which machine is connected. Differences
are summarized in the following table:
One hydraulic ,
Nomenclature of tractor hydraulic parts is based on
their use with the scraper. That's because the scraper
was developed first. However, it's easy to relate tractor
parts to water distributor operation. Simply remember
that the pump and valves that drive the elevator on the
scraper operate the water pump on the water distributor.
The pump and valves that drive scraper cylinders drive
the lift cylinders on the water distributor. For ease of
understanding, water distributor nomenclature has been
added in parenthesis immediately following scraper
The motion required of the water distributor water
pump differs from that of the scraper elevator. For the
water pump, no reverse motion or low
speed is necessary. Because of that, the tractor
elevator circuit operates only in FORWARD direction at
HIGH SPEED when a water distributor is connected.
operation of a scraper and that of a water distributor.
When a water distributor is used. tractor lines that
would feed scraper door and ejector cylinders are
The tractor has two hydraulic pumps, located on the
torque converter housing. Each is a two-section vane-
type pump. Oil flows from the pumps to valves which
control water distributor or scraper functions. The
valves are actuated by levers at the right of the
operator's seat (in the tractor cab). Flexible cables (with
covers) connect the levers to spools inside the valves.
When the control levers are in HOLD position, with
the engine running, all oil goes through the control
valves back to the oil filter in the hydraulic tank. From
there it passes into the tank.
The oil filter has a bypass valve. If the filter element
gets too dirty, and the oil can not easily go through the
element, there is an increase in the pressure of the oil to
the filter. High oil pressure opens the bypass valve and
the oil goes through the open bypass valve into the tank.
Cold hydraulic oil can not easily go through the filter
element. The increased pressure of the cold hydraulic
oil keeps the bypass valve open until the oil gets warm
which decreases the oil pressure and closes the bypass