ARTICLE
Energy efficient fan drives like the compact A1VO provides opportunity to switch to a variable fan drive system which uses hydraulic power on as it is needed .
Driving multiple pump stack ( s ) in a system can also be accomplished by utilizing pump through drives . Most axial piston pumps offer a through drive option to allow for mating an additional pump to the back . These through drives are available in various sizes to allow for different mounting flanges such as SAE , A , B , C , or other standards . Many combinations can be created by this method , but one must consider the available maximum torque levels each pump or thru-drive can provide to the additional mounted pump . As well , there are maximum limitations in regards to bending moments / weights / lengths of the pump stack ( rear support of the stack ( s ) may be necessary ) and a limitation of the torque available at each pad .
Other considerations
Even with the cases mentioned , there are still other elements of the machine design that should be considered for determining the input method to the hydraulic pump . The impact of Tier IV final emissions on machine design should be considered . The additional engine exhaust after treatment systems will take up more real estate on mobile equipment . This will present new challenges for hydraulic systems as more pumps with higher power density will be required due to space limitations . These power dense pumps may be operating at higher pressures that may alter how the pump should be driven within the system .
Additionally , it is now well known that the upcoming Tier IV final engines show a more demanding torque / load ripple effect due to the higher injection pressures . As pumps are used on direct engine drives as well as PTOs , it is important to consider the amount of angular acceleration ( rad / s2 ) fluctuation of the driven pump input . Most pump manufacturers have published limits of angular acceleration that the input shaft can withstand .
In summary , manufacturers of both On- and off-Highway equipment must consider the desired functionality of the machine while evaluating the best approach to transfer the engine power to the desired function . The pump drive is a key decision in the layout of the machine and overall performance for the OEM . Depending on where the hydraulic work is performed , e . g . at the cylinders on a boom or the wheel drives of a loader , the freedom that hydraulics provide allow the designer to place his components in multiple locations on a machine which cannot be surpassed by any mechanical drive . Pumps can be placed with complete disregard to the point of power usage . This is one of the major reasons designers of mobile machinery will continue to use hydraulics for years to come .
Hydraulics are used for many different mobile machine functions , all of which require a pump that provides the flow to accomplish the intended work . There are many options for where that pump is located , dependent upon the availability of a mechanical rotational power source to drive the input shaft of the pump . www . boschrexroth . com
may 2018 Global MDA Journal 27