Excavator, the Cream of Structural Design

Introduction

One way to learn design is to observe existing products. By critically observing a design and paying attention to its details, we can trace back the reason for decision making behind the design. My favorite product of structural design is: excavator. It is the cream of structural design. Most of today excavators still carry the legacy of old-school designers who have strong engineering intuition. Their structural details are simple and straightforward yet elegant. Their shapes are balance between strength, functionality, ergonomics, and ease of fabrication.

Komatsu PC 2000

Let’s see one example shown in Figure 1 below: Komatsu PC 2000. This picture was snapped on October 2007 in Kemayoran, Jakarta. It shows the PC 2000 in action. Since I am only interested in its superstructure, I only took some pictures beneath the upper machine (Figure 2, 3, and 4).

Fig. 1. Komatsu PC 2000.

Figure 2 is an upward view from beneath the upper machine. It shows various bolted and weld joints with clean and effective shapes. Figure 3 shows the rear section of PC 2000 undercarriage. It shows how various tubing lines are neatly integrated into the structural design. Figure 4 shows the front section of undercarriage. It shows bolted joint between center frame of undercarriage with crawler frame.

Fig. 2. Upward view from beneath PC 2000 upper machine.

Fig. 3. Hydraulic and grease tubings integrated into undercarriage structure.

Fig. 4. Details of crawler frame.

Terex RH 30-F

Excavator I am most familiar with is Terex RH 30-F, which is shown in Figure 5 below. I designed and supervised the construction of its slewing ring and pedestal support. Figure 6 shows the slewing ring during installation. I also witnessed the real power of a mining excavator in this project. RH 30-F has breaking force of 40 tons at the tip of its bucket.

Fig. 5. Terex RH 30-F installed on a movable gantry.

We installed the machine on a movable gantry running along a 300-ft coal barge. When it pulls the coal, the whole structure on which it sits on shakes like earthquake. This is something you won’t experience in ordinary excavator working on the ground. It is extremely powerful. Be careful when you design structure for a mining excavator. In brief: mining excavators are not just a pretty machine, they are very, very powerful mechanical beasts.

Fig. 6. Installing slewing ring and pedestal support for Terex RH 30-F.

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