Hydraulic Excavator Upper Structure


This project has everything. IC engine and hydraulic systems, wire harnesses, sheet-metal, weldments, castings, plastics, the works. My experience at Deere Hitachi, tells me that it would take about a year to re-create a CAD model of the John Deere 270D LC upper structure assembly and drawings. Assuming we have 3D files for purchased parts. And assuming there are no major design changes.

But minor design changes will be many and frequent, so the primary goal of this project is to create models with easily modifiable geometry to help speed up product design iterations.

My secondary goal is to periodically post project updates and special requests.

Completed Project Tasks

First I gathered all available data to most accurately and cheaply model the upper structure. A brochure downloaded from John Deere is providing technical specifications and dimensional proportions of parts and equipment. I found dozens of 3D iges models on a site called GrabCad.com (thanks again). None of the models are from a 250D machine, but they similar enough for my purposes.

Sorted through imported models to find the best lower structure and boom assemblies. Two good models, one with detailed crawler feet and another with a well detailed bucket. Both sub-assemblies had to be scaled to fit a 270D LC excavator. Six iges parts in assembly had missing surfaces and needed to be fixed.

I intend to control the size and shape of the upper structure and cab body panels with a (single) master model. Outer surfaces of this model will become the excavator body. The surface features propagate by associative copy to panel instances throughout sub-assemblies and 2D drawing views. Therefore, my second task is to create a CAD model of the upper structure and cab. See Source Part images, in list number 1 below.

The next task is to make an associative copy (and context assembly) of the part model. For now, the resulting upper structure assembly consists of just part copies. Eventually, the parts will become Nx Ideas sheet-metal parts in sub-assemblies with brackets and hardware. Right now, the cab assembly also consists of just parts, a chair, joystick and model of the cab body.

After parts become Nx sheet metal parts, additional panels, fillets, and stamped features like lips, louvers, bosses, and stiffening bends, can be added where needed.

Forth completed task is to create a frame for the upper structure. The frame assembly has a main weldment and body-panel frame sub-assemblies. The counterweight, engine, and hydraulic pumps are supported by a heavy-steel main frame. Lighter steel cross-members and side rails are welded to the main frame to help support the cab, accessories, and body panels. See frame drawings through links below.

CAD model 2D image and drawing galleries

  1. Source part
    1. October 28, 2018
  2. Frame and body drawings
    1. October 28, 2018
    2. March 30, 2019
  3. Engine and hydraulic pump accessories
    1. March 30, 2019
  4. Brackets
  5. Compartment structure panels
  6. Hydraulic hoses and pipes
  7. Wire harnesses

Project tasks to do

The purpose of this website is to showcase my CAD talents. Future post will have examples of packaging, sheet metal design, and harnessing. The following tasks will not necessarily be completed in this order.

The first task is to download iges models of engine, heat exchangers, pumps, motors, and everything else in a hydraulic excavator, but not in list above. Things I cannot find, will have to be created from scratch and may be limited in detail.

Add engine, hydraulic pumps and other CAD models to upper structure assembly. Locate engine, centered just in front of counterweight, with end of driveshaft pointed to the right toward pumps. Design engine mount brackets and transmission from engine to pumps. I don’t know exactly how power is transmitted from engine to the pumps… yet.

Layout interior-compartment-panel structure around frame, body panels, and equipment. Most exterior panels have doors, so I will re-create door hardware and brackets. Start with engine compartment panels, then move left to doors in front of heat exchanger. On the other side of the machine is the pump compartment, also with an access door. Compartments for the oil and fuel tanks and the tool box are forward of the pump compartment. Finally, two compartments behind the cab (with doors).

Design route of engine fuel and electrical delivery systems.

Route hydraulic lines.