HSD versus HST transmissions

[MapleLeafFarmer]

I read a thread on a guy who had a B series tractor with an HSD transmission.

Never heard of HSD

Are they basically same as a HST or are they different somehow?

 

[TheOldHokie]

I read a thread on a guy who had a B series tractor with an HSD transmission.

Never heard of HSD

Are they basically same as a HST or are they different somehow?

View attachment 168496
View attachment 168497

HSD is a model designation

EXAMPLE

L3901HSD

L3901 = base model
HS = HST transmission
D = dual traction (4WD)