This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of Hydromechanical Transmission (HMT) for Bulldozers
Annotation ability available
Sector:
Language:
English
Abstract
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.
Recommended Content
Technical Paper | A Double Planetary Gear Train-CVT Transmission with Multiple Applications |
Technical Paper | Power Train and Accessory Standards |
Technical Paper | Hybrid Optimization Methodology for Flexplate of Automatic Transmission |
Authors
Topic
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.Also In
References
- Kusaka K. Ohkura O. “A Transmission Control System for Construction Machinery” SAE 901557 1990
- Nakamura K. Mihara K. Kibayashi Y. Naito T. “Improvement on the Fatigue Strength of Case Hardened Gears by a New Heat Treatment Process” SAE 821102 1982
- Akamatsu Y. Tsushima N. Goto T. Hibi K. Itoh K. “Improvement of Roller Bearing Fatigue Life by Surface Roughness Modification” SAE 910958 1991