I-2 / I-3 Valve Reference Material
August 2019 - 89130 v.3.0 61
Sequence of Events
(continued)
Down Slowdown and Leveling
1. To change to leveling speed, the down fast solenoid closes. The lowering piston starts
in the full open position, and the piston skirt blocks the oil passage to the tank. See
Figure 12.
2. Oil flows in through the down stop adjustment to the rear of the lowering piston, and
out through the slowdown adjustment. The down slow solenoid and the down start
adjustment cause the lowering piston to move toward the closed position. The amount
that the down slowdown adjuster is closed governs the speed at which the piston
moves and the car slows down.
3. The piston stops when the piston skirt opens the oil passage to the tank through the
down slow solenoid.
4. To control the lowering speed, turn the lowering and leveling adjustment in increments
of half-turns. To control the leveling speed, turning the lowering and leveling adjust-
ment in increments of less than one-quarter turns.
Figure 12 - Down Slowdown and Leveling Diagram
TANK
PUMP JACK
Lowering Piston
Down Slow
Solenoid (Open)
Down Start
Adjustment
Manual Lowering
Down Slowdown
Adjustment
Down Fast
Solenoid (Closed)
Lowering Speed Adjustment
Down Stop Adjustment
Check Valve Piston
CONTROL FLOW
MAIN FLOW
Piston Skirt
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