Fings wot broke

[AHPP]

I do get that my criticisms are largely academic. Ten thousand disc woodchippers are going to work absolutely fine at ten o'clock tomorrow morning.

[Mick Dempsey]

I guess weight and ease of manufacture is a factor as well. 
 

[AHPP]

https://vermeeruk.co.uk/blog/drum-wood-chippers-vs-disc-wood-chippers-which-is-better-

 

[PeteB]

I did a power point presentation to explain all the different types of chipper and their pros and cons. A drum is a good way to get a bigger capacity without a wide machine as a disc is over twice the width of the chipper capacity. A disc style machine has a decent amount of centrifugal forces helping to keep it going and can easily produced the puff to blow woodchips and are easy to produce and assembly where a drum may need more assembly/fabrication time and have the need for an extra blow system to blow the chips. The majority of hand fed Chippers are the disc style and yes, the bearings let go eventually, some may consider this as planned obsolescence but by the time they got a rumble on, they have done a few shifts!