Question

5. A CAT 329D excavator is digging a trench in a rock ledge. The trench is rectangular, 1.5 m wide and 6 m in depth. The load factor for the rock is 0.75. The bucket has a heaped capacity of 1.25 m3 and a bucket fill factor of 0.8. The spoil pile has an angle of repose of 2H:1 V. Maintain a separation of 0.6 m between the spoil pile and the edge of the trench. The excavator has a horizontal reach of 11.5 m from the center of rotation to the tip of the bucket when fully extended and a maximum digging depth of 8.15 m. The rock that is being excavated from the trench was very well fragmented from blasting. One laborer is working in the vicinity of the trench. Otherwise, there are no other obstructions. Estimate the productivity of this trenching operation in bank cubic meters per hour. The only job the excavator has to accomplish is digging the trench. Excavator Productivity Worksheet Selected Excavator ∠AT329D Heaped Capacity: Stick length: Material: Type: Depth of Excavation: Bucket Type: Max Digging Depth: Width: \% Max Depth: Tip Radius: Max Reach: Swing Angle Diagram: Productivity =

Answer 1

The productivity of a CAT 329D excavator in digging a rock trench can be estimated by considering the effective capacity of the bucket per cycle and the number of cycles per hour. With a heaped capacity of 1.25 m³, a bucket fill factor of 0.8, and a load factor of 0.75, the effective bucket capacity is 1.33 BCM. Assuming a 2-minute cycle time, productivity is approximately 39.9 BCM/hour.

Step-by-step explanation:

To calculate the productivity of a CAT 329D excavator when digging a trench in a rock ledge, we need to consider the dimensions of the trench, the load factor of the material, the bucket capacity, the fill factor, and the operational capabilities of the excavator.

The trench is 1.5 m wide and 6 m deep. The bucket has a heaped capacity of 1.25 m3 and a fill factor of 0.8, so the effective capacity of the bucket when digging rock will be 1.25 m3 × 0.8 = 1.0 m3. The load factor for the rock is 0.75, hence each bucket load will contain 1.0 m3 / 0.75 = 1.33 bank cubic meters (BCM) of rock.

The productivity, as the number of buckets filled per hour, can be estimated by the cycle time of the excavator, which typically includes digging, swinging to the spoil pile, dumping the load, swinging back to the trench, and positioning for the next dig. Without specific cycle time provided, the estimation can only be general. As an example, if a complete cycle takes 2 minutes (which is a common estimate for this kind of operation), the hourly productivity would be 60 min/hour divided by 2 min/cycle × 1.33 BCM/bucket = 39.9 BCM/hour.

This is a broad estimation and actual productivity can vary based on efficiency, operator skill, and site-specific conditions (such as proximity to the spoil pile and any obstructions).

Answer 2

The productivity of a CAT 329D excavator in trenching operations is determined by calculating the effective capacity of the bucket, the volume of the trench segment, and accounting for the load factor for the rock. The number of bucket loads required is found based on these calculations, which must be combined with the cycle time per digging operation to estimate productivity in bank cubic meters per hour.

Step-by-step explanation:

To estimate the productivity of the trenching operation of a CAT 329D excavator, we must consider several factors, such as the heaped capacity of the bucket, bucket fill factor, load factor for the rock, and the dimensions of the trench. The bucket's effective capacity can be calculated by multiplying the heaped capacity of 1.25 m3 by the fill factor of 0.8, resulting in an effective capacity of 1 m3. Given that the trench is 1.5 m wide and the excavator can operate efficiently up to 6 m in depth within its reach, we can determine the volume of rock that needs to be removed per trench segment.

Considering the load factor of 0.75, the bank cubic meter (BCM) of rock in each trench segment can be found by multiplying the volume of the trench by the load factor. This value is then divided by the effective capacity of the bucket to find out how many bucket loads are required to excavate the trench segment. To give a complete answer, we would need to know the cycle time for each digging operation and how many cycles the excavator can complete in an hour to calculate the hourly productivity in BCM/hour.