Grove Published 04-04-2017, Control # 446-09 3-35
RT770E OPERATOR MANUAL OPERATING CONTROLS AND PROCEDURES
rear axle does not lock or unlock properly, evaluate the
lockout system and repair as necessary.
General Crane Operation
Pump Drive
The main hydraulic pumps are mounted on the torque
converter drive pad. The pumps operate any time the engine
is running.
Control Lever Operation
The control lever operation for all crane functions is
standard, i.e. the closer the lever is to neutral (center), the
slower the system responds. The control lever should be
returned to neutral to hold the load. Never feather the hoist
control lever to hold the load.
NOTE: Always operate the control levers with slow, even
pressure.
Preload Check
After the crane has been readied for service, an operational
check of all crane functions (with no load applied) should be
performed. The Preload Check is as follows:
NOTE: Operate engine at or near governed RPM during
preload check of crane functions.
Carefully read and become familiar with all crane
operating instructions before attempting a preload
check or operating the crane under load.
1. Extend and set outriggers.
2. Raise, lower, and swing the boom a minimum of 45°
right and left.
3. Telescope the boom in and out.
4. Raise and lower the cable a few times at various boom
lengths. Ensure there is no kinking.
Using Your Load Chart
NOTE: One of the most important tools of every crane is
the Load Chart found in the crane operator cab.
The Load Chart contains a large amount of information,
which must be thoroughly understood by the operator.
The Load Chart contains outrigger capacity charts for fully
extended, mid extended outriggers for the main boom and
boom extension, and fully retracted outrigger beams for main
boom only. In addition, the Load Chart contains two on-
rubber capacity charts: 360° stationary, and pick and carry
over front.
The Load Charts are divided into structural strength and
stability limits. This is shown by the bold line across the chart.
Capacities above the line are structural strength limits and
capacities below the line are stability limits.
The left column is the load radius, which is the distance from
the center of crane rotation to the load center of gravity. The
top row lists various boom lengths ranging from fully
retracted to fully extended or boom extension lengths and
offsets. The number at the intersection of the left column and
top row is the total load capacity for that load radius and
boom length or boom extension lengths offset. The number
in parentheses below the total load capacity is the required
boom angle (in degrees) for that load. When the boom length
or lift radius or both are between values listed, the smallest
load shown at either the next larger radius or next longer or
shorter boom length shall be used.
Another important section is the range diagram. The range
diagram shows the operating radius and tip height that can
be achieved at a given boom length and angle. If the
operator knows the radius and tip height required for a
specific lift, the angle and boom length can be quickly
determined from the range diagram. Or, if the boom length
and angle are known, the tip height and operating radius can
be quickly determined.
A lifting diagram is included to describe over side, over rear,
and over front lifting areas. The lifting area diagram shows
that the locations of the outrigger jack cylinders in the fully
extended position are used to mark the boundaries of the
lifting areas.
A boom extension capacity chart and notes are included to
list the capacities for the extension length, load radius, and
boom angle.
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