Engineering the Engine Puller/Block Cracker for Nye Manufacturing
My role in the design and manufacture:
Work began on this project after a local scrapyard reached out to the company I was working for at the time Nye Manufacturing Ltd.
This particular scrapyard would routinely recycle automotive engine blocks by pulling them from the automobile and then crushing them to sort out the ferrous from non-ferrous materials using an electromagnet. They originally only wanted an engine pulling and stripping tool which they could mount to the end of one of their hydraulic excavators. But soon after receiving the original EXT200 Engine Puller they again reached out to us this time requesting an Engine Block Cracking Tool, and we were more than happy to produce the EBC200. Below is a more detailed description of how we developed both tools, including some of the engineering design work behind the scenes.
Right away we began looking at existing designs of engine pullers on the market. Most were stationary, in the sense that they were not able to rotate at all. This meant the operator was limited in the overall range that tool could be used. We knew ours would have to rotate 360 degrees, which was accomplished with a Rotobec 360 degree rotator.
Another consideration was the intent of the tool. Most auto recycling facilities spend a majority of their time stripping old cars of the valuable resources (wiring which has copper, alloys used in the engine/drivetrain, removing hazardous fluids, etc..)
This meant a nimble and dexterous tool was required, something almost fingerlike to pick and pull smaller pieces from the automobiles. This is where the shape of the engine puller came into place.
I decided to go for a staggered and welded plate design, meaning that flame-cut plates of QT100 steel could be layered in varying thickness’ and shapes. This also kept the cost of construction down vs going the route of casting and then machining after, which is more common.
One other consideration was cutting of material. To accomplish this a set of shear blades would be incorporated into the moving and stationary sides of the extremities. Bowe Machine Co. supplied the shear blades. They a well known shear blade manufacturer who was known to supply such manufacturers as LaBounty, Genesis.
The main pivot is a single 6″ Dia. alloy pin made from 4340 HTSR alloy steel in combination with greaseable aluminum bronze bushings.
To produce the force required for shearing of steel two massive 6″ diameter hydraulic cylinders were used at an operating pressure of approximately 4500PSI (STD for hydraulic excavators). This meant that a force of roughly 127,234.50 LB per cylinder is produced, a total of approximately 254,469.00 LB. More than enough for to cut steel rebar, even railroad tracks as we found out during testing.
Machining tolerances were held fairly tight as the shear blades need almost perfect alignment to function properly. Pockets for the blades were CNC machined into the extremities and shim plates of varying thicknesses installed under the blades allowed for fine tuning of the cutting faces.
The engine block cracker is basically the same as the engine puller, main difference being the crushing jaws instead of the precise pincers that engine puller has.
The idea behind the engine block cracker comes from crushing and cracking the old cast engine blocks to remove the more valuable alloy metals inside, which are typically much tougher and survive the cracking process.
Jaw construction is mainly QT100 structural steel, the crushing teeth are made from AR400 abrasion resistant steel.
The design software used on this project was Solidworks.