Hogzilla in operation. The funnel shaped hopper and the tub below rotate slowly. Inside the tub are a set of fins like the tub of a clothes drier that pull the wood around. In the stationary floor is a mill, a set of rotating steel hammers that quickly pulverizes the wood to pieces small enough to fall through a grate to a conveyer that sends the output to a mulch pile. That's wood smoke drifting out of the tub. When the wood jams up on the mill, friction burns the wood. The machine can detect a jam and automatically reverse the drum rotation to clear it.

 

 

 

Feeding Hogzilla takes a really big fork!

 

 

Say Aahhh! Hogzilla is a fast eater. The backhoe operator has to keep moving to keep the tub filled. He can also control all aspects of the tub grinder by radio control while in the backhoe cab.

 

 

Dropping in another load. The tub grinder's ability to process lumber quickly is due to its huge proportions and power. The tub is about 12 feet across. The mill is driven by a 1,500HP engine!

 

 

Here's the output end of the machine. There's a constant flow of mulch. CW Manufacturing's web site says that production rates up to 200 tons per hour are possible.

 

 

 

Stand clear! With the tub nearly empty, the spinning mill can pitch out huge chunks of wood at high velocity.

 

 

Done for the day. The operator shuts down the engine by remote control. The bulldozer is used to tow Hogzilla on the job site. Between jobs, Hogzilla can be moved on the interstate highways, towed by a semi-tractor.

 

 

Into the belly of the beast! This is the mill. It's a set of huge spinning hammers that pulverizes the wood. It was still turning slowly when I took this shot. The piece of wood bridging  the mill is about 6 feet long.

 

 

 

On day two, the machine is down for maintenance. It's a rare opportunity to take a peek inside.

 

 

 

 

A view from the mulch pile. Still plenty of work left.

 

 

 

All this will get processed after repairs are made.

 

The front of the machine is like a screened in porch. Debris and grit are filtered out and the main engine air filter intake draws air from this space.  The compartment also houses a utility compressor that supplies service air for maintenance tools like impact wrenches. There's a small engine in the space that powers the compressor.

 

 

The hood is up. You're looking at the bottom of the tub. There's a large hydraulic cylinder to the left of the mill that raises and lowers the tub.

 

 

 

You can see the fins in the tub. They drag the load of wood around with the rotating drum, over the mill.

 

The drum drive is a large hydraulic motor. A jam is detected by a rise in hydraulic pressure. This automatically triggers a valve sequence that changes the direction of rotation. The operator can also directly control these functions.

 

 

The control panel. There are a lot of hydraulic and engine systems to monitor. The operator can control it all by radio when the machine is running.

 

 

A clear picture of the mill and grate. The grate can be easily changed to one with different size openings so the same machine can yield different grades of mulch. The space outside the grate leads to the conveyer.

 

 

Here's the problem. Notice the missing hammer head on the second hammer from the right. A new one will be bolted on.

 

 

The orange strap around the drive shaft isn't a bearing support. It's a retainer or safety collar. It keeps the drive shaft from flying out of the machine should the shaft coupling at either end break.

 

The engine drives the mill through a torque converter seen here. It's similar to the one in your automatic transmission. A short drive shaft connects the torque converter to the mill. The large hoses are hydraulic lines that power the tub motor and conveyer system.