Cat 311D LRR: stick choices, tool circuits and rear clearance

The 311D LRR front is a choice, not one digging envelope

Cat's March 2008 publication pairs the 4.3 m reach boom with three sticks. The short 2.25 m stick is shown with a 0.52 m³ bucket; the 2.6 m and 2.8 m sticks use a 0.40 m³ bucket in the working-range table. A reach comparison that ignores those bucket assumptions combines different front configurations.

The longer stick extends the excavation envelope but reduces the published stick digging force. Maximum reach is not a lifting capacity.

The transport drawing also changes with stick length. Its short-stick shipping height is 2860 mm, rising to 3020 mm for the intermediate stick and 3160 mm for the longest one. A separate general specification row prints 2830 mm.

Keep the dimension tied to its table and transport arrangement; the general row does not erase the front-specific drawing. Cab height and boom shipping height are different measurements.

Separate travel pressure from attachment supply

The 5076 psi entry belongs to travel. Implement pressure is 4424 psi, and swing uses another limit. Calling the travel figure a universal hydraulic relief pressure overstates what a digging attachment receives.

The main implement specification describes two pump flows, each rated 117 L/min; it is not a promise of that combined flow at every work-tool connection.

Optional circuit equipment determines the tool connection. Cat's Combined System permits one- or two-pump flow in either one or two directions. Priority Flow is a separate option for tools needing their hydraulic supply prioritized.

A medium-pressure circuit serves functions such as bucket or shear rotation. Tool Control can retain ten tool settings, but a saved setting does not establish which valves and lines are installed. Check the physical circuit before selecting a hammer, mower or rotating tool.

Reduced rear swing and service access

The LRR counterweight swings within the track length, according to Cat's versatility description. That rear clearance does not constrain the bucket or boom to the same space. The X-shaped carbody and grease-lubricated track belong to the undercarriage; neither changes the clearance required by an extended front.

For maintenance access, the radial-seal air cleaner sits behind the cab. Its restriction warning appears on the monitor. The hydraulic return filter is a capsule accessible from outside the tank, while the Cat ET connection is inside the cab.

Those locations help distinguish an air-filter warning, hydraulic filter service and electronic diagnosis during an inspection. Economy mode is selected on the monitor; Cat describes it as retaining breakout force and lift capacity while balancing performance and fuel use.