Wheeled excavators lack the large-area ground contact support of crawlers, and their operational stability depends entirely on the rational deployment of outriggers, effective ground load-bearing capacity, and center-of-gravity control of the body. The core control principles for outrigger deployment are "all outriggers on the ground, even force distribution, symmetrical deployment, and terrain adaptation". Practical operational points are formulated from five dimensions: pre-operation survey, standardized outrigger deployment, scenario-specific adaptation, stability recheck, and operational taboos. These points completely avoid problems such as outrigger subsidence, body rollover, and operational shaking, ensuring stability during heavy-load excavation and high-altitude operations. The specific operational requirements are as follows:

I. Pre-operation Preparation: Ground Survey + Equipment Inspection to Fundamentally Avoid Outrigger Instability

The stability of outrigger deployment is based on ground load-bearing capacity and equipment condition. Two core preparatory tasks must be completed before operation to prevent subsequent instability caused by ground collapse or outrigger malfunctions:

Ground Survey and Load-bearing Assessment

Confirm the ground material of the operation area (hardened concrete/asphalt, plain soil, soft muddy ground) and mark weak points such as hidden ditches, manholes, and backfilled soil areas. For plain soil or soft ground, lay thick steel plates (≥10mm), sleepers, or road base boxes at the outrigger landing points in advance (the laying area is ≥ twice the size of the outrigger base plate) to disperse the concentrated pressure of outriggers into uniform ground pressure and prevent outrigger subsidence. For hardened ground, check for cracks and hollowing to avoid placing outriggers on hollowed areas.

Outrigger System Equipment Inspection

Check for oil leakage or jamming in outrigger hydraulic cylinders, ensure outrigger base plates are intact (no deformation or damage), and verify that outrigger telescopic mechanisms are not loose. Switch the excavator to operational mode (non-travel mode), test the smoothness of outrigger telescopic movements, and confirm the effectiveness of outrigger locking devices. Never conduct operations with faulty outrigger components.

Operation Surface Planning

Plan the outrigger deployment position based on the excavation direction and operational radius. Ensure the body remains parallel to the operation surface after outrigger deployment, and the reaction force direction of excavation aligns with the outrigger support direction to avoid eccentric loading.

II. Core Specifications for Outrigger Deployment: Symmetrical Operation + Full Ground Contact + Step-by-Step Leveling for Even Force Distribution

Outrigger deployment must follow the steps of "first symmetrical deployment, then ground contact; first leveling, then operation". Unilateral rapid deployment, outrigger partial contact, and body tilting are strictly prohibited. All movements must be low-speed, stable, and phased. The core content includes basic deployment steps and key leveling points, applicable to all conventional operational scenarios:

(I) Basic Outrigger Deployment Steps (Four-outrigger models are industry mainstream and taken as the core)

1. Initial Positioning: Park the excavator at the center of the operation area, engage the parking brake, cut off travel power, and lower the working device to the ground (the bucket touches the ground lightly to share part of the body's self-weight), keeping the body in a temporarily stable state to prevent sliding during outrigger deployment.

2. Symmetrical Deployment of Outer Outriggers: Operate the outrigger control valve to deploy the left and right outer outriggers at low speed simultaneously (no sequence required), allowing the outrigger base plates to lower slowly until they are fully attached to the ground (no suspension or warping). Extend the outrigger hydraulic cylinders to 80%-90% of their stroke (reserve a buffer stroke to avoid overload).

3. Symmetrical Deployment of Inner Outriggers: After the outer outriggers make ground contact, deploy the left and right inner outriggers at low speed simultaneously in the same manner until the base plates are fully attached to the ground and all outriggers are under load. At this point, the excavator tires must be completely off the ground (a key point; operations with load-bearing tires are strictly prohibited).

4. Overall Body Leveling: Fine-tune individual outriggers to level the body (based on the level gauge in the cab; if no level gauge is available, observe the boom and body frame to ensure no left/right or front/back tilting). After leveling, reset and lock the outrigger control valve to prevent accidental telescoping during operation.

(II) Key Leveling Points for Outrigger Deployment

1. Leveling Priority: Level the left and right sides first, then the front and rear. Left/right tilting can cause body rollover during excavation, the most dangerous instability factor, and must be prioritized. Front/back tilting should be controlled within ≤3° to prevent body sliding during excavation.

2. Single Outrigger Fine-tuning Principle: Only make small telescopic adjustments to a single outrigger during leveling (≤5cm per adjustment). Simultaneous adjustment of multiple outriggers is prohibited to prevent sudden changes in the body's center of gravity. For uneven ground, adjust by laying base plates instead of over-telescoping outrigger hydraulic cylinders.

3. Base Plate Adhesion Requirement: Outrigger base plates must be in full contact with the ground with no gaps or slippage. Remove gravel and debris between the base plates and the ground in a timely manner to prevent outrigger subsidence caused by base plate slippage during operation.

4. Tire Ground Clearance Standard: After all outriggers are deployed, tires must be 5-10cm off the ground. This ensures full load-bearing by the outriggers while avoiding center-of-gravity offset caused by excessive tire suspension.

III. Scenario-specific Outrigger Deployment Points: Targeted Adjustments for Eccentric Loading/Complex Terrain

Wheeled excavators often face scenarios such as unilateral heavy-load excavation, high-altitude operations, and uneven terrain. The outrigger deployment method must be adjusted based on the operational force characteristics, following the core principle of "strengthen support for outriggers on the force-bearing side, maintain stability for outriggers on the non-force-bearing side, and strictly prohibit single outrigger loading on one side". Adaptations for common scenarios are as follows:

1. Conventional Front Excavation (No Eccentric Loading): Follow the basic deployment steps with even force distribution on all four outriggers, a level body, and consistent outrigger stroke. Ensure the excavation force is transmitted directly to the outriggers and ground—this is the most stable outrigger deployment mode.

2. Unilateral Heavy-load Excavation (e.g., left/right side excavation, slope operation): ① Fine-tune the outriggers slightly toward the force-bearing side to tilt the body gently (≤2°) toward that side, making the outriggers on the force-bearing side bear the main load; ② Add extra thickness or increase the laying area of the base plates for the force-bearing outriggers to prevent subsidence; ③ Keep the outriggers on the non-force-bearing side fully on the ground (never retract them) to ensure lateral body stability.

3. High-altitude Operations (e.g., boom lifting, high-altitude obstacle clearance): ① Fully deploy all four outriggers and level the body to the maximum extent, extend the outrigger hydraulic cylinders to the rated stroke, and lock all outriggers; ② Control the slewing radius of the working device within ±30° directly in front of the body—large slewing to both sides of the body is strictly prohibited to prevent the center of gravity from shifting beyond the outrigger support range; ③ Lay double-layer base plates at the outrigger landing points to enhance ground load-bearing capacity.

4. Uneven Ground (≤15°): ① Adopt the "base plate leveling method": lay base plates at the outrigger landing points on the low side to keep all outrigger base plates on the same horizontal plane. Never compensate for ground unevenness by over-telescoping outriggers (the telescopic difference of outrigger hydraulic cylinders ≤10cm); ② Deploy the outriggers on the sloped side first to ensure the base plates make ground contact, then deploy the outriggers on the other side and level the body gradually.

5. Narrow Space Operations (Limited Outrigger Deployment Space): ① If full deployment of four outriggers is impossible, adopt the mode of "half-deployed outer outriggers + slightly deployed inner outriggers", ensuring the outer outriggers are fully on the ground with tires off the ground, and the inner outriggers only need to be attached to the ground (no full extension required); ② Strictly control the excavation force and operational radius—heavy-load excavation is prohibited, only light-load and small-range operations are allowed.

IV. In-operation Stability Recheck and Maintenance: Real-time Inspection to Avoid Dynamic Instability

Outrigger deployment is not a "one-time task". During excavation, the body is subject to reaction forces and vibrations, which may cause outrigger loosening and base plate slippage. Real-time inspection and dynamic maintenance are essential to ensure stability throughout the operation:

1. Light-load Test Run for Initial Excavation: After deploying and leveling the outriggers, first conduct light-load and small-range excavation (30%-50% of the rated excavation force) to test for body shaking or outrigger subsidence. Gradually increase the excavation force only after confirming no abnormalities.

2. Regular In-operation Inspection: Check the outrigger status every 10-15 minutes of operation: ① Whether there is oil leakage or retraction in outrigger hydraulic cylinders; ② Whether base plates are slipping or subsiding; ③ Whether the body remains level; ④ Whether outrigger locking devices are effective. Stop operation immediately and readjust the outriggers if any problems are found.

3. Coordination of Excavation Movements and Outriggers: Follow the principle of "from shallow to deep, light excavation and slow slewing" during operation. Sudden heavy-load excavation and large-angle slewing are strictly prohibited—excessive excavation reaction force will cause outrigger loosening due to impact and even base plate slippage. Slew as much as possible within the outrigger support range to avoid the center of gravity shifting beyond the support area.

4. Emergency Handling for Ground Settlement: If slight outrigger subsidence is found (body tilting ≤5°), stop excavation immediately, lower the working device to the ground for support, add extra base plates under the sunken outrigger base plates, and re-level the body. Never continue operation in a sunken state.

V. Standard Specifications for Outrigger Retraction: Reverse Operation for Stable Ground Contact

The retraction operation of outriggers after operation also affects equipment and ground safety. It must follow the steps of "first leveling, then retraction; symmetrical low-speed operation, gentle tire ground contact". Rapid retraction and unilateral retraction are strictly prohibited:

1. First lower the working device to the ground with the bucket touching the ground lightly, restore the body to a level state, and unlock the outrigger control valve.

2. Retract the inner outriggers symmetrically at low speed, allowing the inner outrigger base plates to leave the ground slowly until the outriggers are fully retracted (tires remain off the ground at this point).

3. Retract the outer outriggers symmetrically at low speed until the outer outrigger base plates leave the ground and the outriggers are fully retracted, then lower the excavator tires to the ground slowly (rapid dropping is strictly prohibited to prevent the body from impacting the ground).

4. After all outriggers are fully retracted, inspect the condition of outrigger base plates and hydraulic cylinders, clean soil and debris from the base plates, reset the outriggers to travel state, then release the parking brake and activate travel power.

VI. Core Operational Taboos: Strictly Prohibit Irregular Operations to Uphold the Stability Bottom Line

All instability accidents during wheeled excavator operation with deployed outriggers stem from irregular operations. The following core taboos must be strictly observed as the red line for operational safety:

1. Strictly prohibit operations with outrigger base plates suspended or warped, and never place outriggers directly on the ground without base plates to prevent outrigger subsidence.

2. Strictly prohibit operations with tires on the ground—load-bearing tires will cause body sliding during excavation and fail to disperse loads, leading to a high risk of rollover.

3. Strictly prohibit operations with a single outrigger deployed unilaterally, and never retract outriggers on one side for unilateral excavation—the body will lack lateral support and roll over instantly.

4. Strictly prohibit operations with outrigger hydraulic cylinders fully extended—reserve a buffer stroke to avoid overload damage to hydraulic cylinders caused by excavation reaction forces.

5. Strictly prohibit moving the excavator with outriggers deployed, and never deploy outriggers while traveling to prevent outrigger deformation from impact and body sliding.

6. Strictly prohibit deploying outriggers on soft ground or backfilled soil areas without laying base plates—such ground has poor load-bearing capacity and is highly prone to outrigger subsidence and subsequent body tilting.

7. Strictly prohibit large-scale outrigger adjustments during excavation—any adjustment of outriggers during operation will cause sudden center-of-gravity changes and trigger instability.

VII. Supplementary: Outrigger Deployment Points for Special Models (Three-outrigger / Folding-arm)

1. Three-outrigger models: Deploy the single front outrigger first, then symmetrically deploy the two rear outriggers. Ensure the front outrigger faces the excavation direction directly to bear the main reaction force, and prioritize front-rear leveling during adjustment.

2. Folding-arm wheeled excavators: After outrigger deployment, additionally lock the folding-arm support base. Prohibit the working device from slewing beyond the fan-shaped range supported by the outriggers to prevent the folding arm from driving the body's center of gravity to shift.