Copyright Goodheart-Willcox Co., Inc.
432 Hydraulic Systems for Mobile Equipment
John Deere Base Model 6030 and 7030 Tractors
John Deere manufactured late-model tractors that used a fixed-displacement
LSPC system. These were the 6030 and 7030 base models, produced from 2008
to 2011. The premium models used a variable-displacement LSPC system.
The base model 6030 and 7030 tractors used two pumps. The first was a
low-pressure transmission pump (254 psi) and the second was a high-pressure
hydraulic pump (2973 psi) for steering, brakes, and DCVs. The high-pressure cir-
cuit consisted of a gear pump that used a priority valve. Deere labeled the priority
circuits as one and three. The priority-one circuit included steering and brakes.
After priority-one hydraulic requirements had been met, oil was routed to the
priority-three circuit, which included the three-point hitch, selective control valves
(SCVs), independent control valves (ICVs), and power beyond. The service liter-
ature omitted reference to a priority-two circuit. The SCVs were essentially DCVs
located at the rear of the machine, and ICVs were mid-mounted DCVs used
for loader control functions. When all of the DCVs were in a neutral position, a
pressure-regulating valve dumped oil to the reservoir at approximately 217 psi
(15 bar). When a DCV was actuated, a load-sensing signal pressure was sent to
the pressure-regulating valve, which enabled the system to build the necessary
pressure to operate the actuator.
The John Deere 6M series tractors replaced the 6030 series. The 6M series
tractor also uses a fixed-displacement LSPC hydraulic system. Note that the 6R
uses a variable-displacement LSPC system.
LSPC Systems with Variable-Displacement Hydraulic Pumps
LSPC variable-displacement systems gained popularity in the off-highway
industry in the late 1970s and early 1980s.
• Massey Ferguson introduced LSPC in 1978 on the MF60 loader
backhoe.
• In 1979, Case introduced the 90 series Case tractors with LSPC.
• In 1981, International Harvester introduced the 88 series with a system
called Power Priority Hydraulics, which was an LSPC system.
• In the mid 1970s, Caterpillar introduced the G Series motor graders
that used load-sensing hydraulics.
• John Deere fi rst introduced LSPC on 6000 and 7000 series tractors in
1992, and 8000 series tractors in 1994.
Many late-model machines use LSPC variable-displacement systems,
including many of the agricultural tractors that retail for $150,000 or more.
Case IH started using LSPC in their 2100 series Axial Flow® combines in 1995
and still use LSPC variable-displacement systems in their late-model com-
bines. Caterpillar has used these systems in numerous machines in the past,
but today many of their machines use proportional priority pressure com-
pensated (PPPC), negative fl ow control (NFC), or positive fl ow control (PFC)
systems.