With tractor at half throttle, adjust flow-control valve
on tractor so openers raise and lower at a
reasonable speed. Keep tractor at one-half throttle
for remaining steps.

Note: Faster opener raise/lower increases potential for oil

over-heating, wear and tractor damage.

Engage tractor hydraulics and lower openers. Lock
hydraulic lever on tractor for continuous operation.

Release locking disks

and

. Adjust

pressure-control valve

knob

for opener down

pressure so gauge

is at 600 psi.

While watching gauge

, slowly turn knob

bypass valve

counterclockwise. Adjust bypass

valve

just until needle on gauge

begins to move

down from 600 psi. Use locking disk

to lock

bypass valve at this setting. (See also note below.)

Adjust pressure-control valve

knob

to desired

opener down pressure per “Hydraulic Down
Pressure” on page 52. Tighten locking disks
and

While 600 psi is a good starting point for setting the
bypass valve, if you consistently operate the planter with
low opener down pressure you can set the bypass valve
below 600 psi. If you consistently operate the planter
with very high opener down pressure, you may need a
bypass-valve setting above 600 psi.

Machine Damage Risk:
Failure to use the bypass valve on load-sensing tractors may
cause major tractor damage.

Note: The higher the bypass pressure, the greater the

potential for oil over-heating and tractor damage.
However, for proper opener operation the bypass
valve must be set at least 300 psi above the opener
down-pressure setting when the tractor is at
one-half throttle. Therefore, you should set the
bypass valve as low as possible while staying at
least 300 psi above the opener down pressure
setting.

Figure 149: s/n A1025S+

Hydraulic Down Pressure Valves

29803