Optimum Sizing of Hydraulic Pump in Vibratory Roller Vehicle Propulsion System 2019-26-0105

Vibratory roller also known as vibratory compactor is a construction equipment vehicle designed for soil compaction which increases the load bearing capacity of cohesive and granular soils. Primary requirement from the industry is to achieve the highest unit volume compaction with lowest fuel consumption and lesser operating expenses spent by end users. In typical vibratory rollers, hydrostatic drive system is used for vehicle propulsion which comprises of one variable displacement hydraulic pump and two hydraulic motors connected in parallel. Between the two motors, one is a dual displacement motor at rear axle drive and the other is a single displacement motor at front drum drive to achieve two different vehicle speeds in Travel and Work modes.

This paper describes the hydraulic system design which differs from conventional system by adapting a dual displacement motor at front drum drive to achieve the desired vehicle speed. This new configuration generates four different vehicle speeds by setting different combination of displacements of the two motors using an electrical actuator valve in a particular sequence of mode. By having the new lowest speed mode, which is selected through a switch by the operator, vehicle can climb the higher gradient of >40% for the given engine power and it has been additionally introduced as “Gradient mode” a new feature apart from regular Travel and Work modes of the vehicle.

Benefit from this new system design is the 40% reduction in hydraulic pump displacement size which gives significant cost savings of around 39%, Motor type change from Single displacement to dual displacement and inclusion of actuator valve increases the cost by 5%. Overall, cost savings of around 22% is achieved and additional mode is introduced as a new feature in the vehicle. Also, the reduced pump size helps in reducing hydraulic oil quantity in the system, thereby reducing carbon foot print.