Development of Hydromechanical Transmission (HMT) for Bulldozers

941722

09/01/1994

Event
International Off-Highway & Powerplant Congress & Exposition
Authors Abstract
Content
Conventional medium to large-sized bulldozers have a powertrain comprised of a manually operated powershift transmission connected in series with a torque converter. There is a growing need, however, for a power train that is more efficient and easy to operate, thereby increasing bulldozer productivity.
One answer to this growing demand is the hydromechanical transmission (HMT) developed by Komatsu for medium to large-sized bulldozers. The HMT consists of a powershift transmission combined in parallel with a hydrostatic transmission (HST) featuring a pair of hydraulic units. The HMT has a continuously variable shifting ratio and achieves high efficiency and automatic shifting. Additionally, it has an electronic controller that controls the transmission ratio to maintain engine speed at the maximum power point. As a result, bulldozers with the HMT demonstrate greatly improved productivity over bulldozers with the conventional powertrain. Furthermore, automatic shifting releases the operator from shifting operation, allowing the operator to concentrate on operating the work equipment and thereby reducing operator fatigue.
This paper explains the method of selecting the gear train and hydraulic unit, and provides an outline of the control method.
Meta TagsDetails
DOI
https://doi.org/10.4271/941722
Pages
12
Citation
Mitsuya, H., Otani, K., Ishino, T., Maruyama, R. et al., "Development of Hydromechanical Transmission (HMT) for Bulldozers," SAE Technical Paper 941722, 1994, https://doi.org/10.4271/941722.
Additional Details
Publisher
Published
Sep 1, 1994
Product Code
941722
Content Type
Technical Paper
Language
English