In Part 2 of an article on the selection of appropriate pump drives, jbj Techniques looks further than the initial six primary considerations for machine builders that were covered in Part 1, and expands on a variety of associated considerations that should be borne in mind.
Beyond the six factors previously outlined, there are some other considerations that should be taken into account when selecting a gearbox or a power take-off unit of any kind - not just a pump drive. When selecting a PTO, the following things should be kept in mind.
Type of prime mover
A gearbox and PTO designed for use with diesel engines will not work as well with a hydraulic prime mover, for example. The type of prime mover must be considered carefully when selecting a PTO. Make sure to choose the right gearbox for a diesel, or petrol engine, or electric-powered or hydraulic motor.
Inertia of the machine to be driven
A high-inertia machine will typically put more stress on a gearbox, due to the heavy torque loads and weight applied to the unit during each rotation. The heavier the pump or other machine is, the more robust the gearbox will have to be. Special bearings and housing designs may be required to accommodate these high loads on the input shaft. This guide is a helpful resource for analysing inertia, engine type, horsepower, and more.
Peak torque requirements
Care should be taken not to undersize or oversize a gearbox. Using power take-offs that are too large - or small - for a particular task will result in higher strain and efficiency losses.
Number of clutch engagements per hour and duration of each engagement
More durable units are required for use in applications such as heavy-duty pumping, milling, and other activities which require fast, repeated clutch engagement every hour.
In some cases, a single power take-off may not be the right choice for a particular application, and multiple power take-offs can be used to provide maximum efficiency, and minimise equipment redundancy. Splitter gearboxes, or multiple power take-offs, allow for a single prime mover to drive multiple pumps or other pieces of equipment. They can even be designed to accept inputs from multiple prime movers, and output to a single application, creating a dual drive input.
Splitter gearbox selection is defined by all of the above statements but care should also be taken to ensure that the unit has a suitable distance between output centre lines to ensure space for pump oil-feed connections. It should also be noted that by selecting a speed increasing ratio within the splitter may allow for the selection of smaller capacity pumps that will still ensure that the flow capacities of the drive are met. Due to potential overhung loads exerted upon the gearbox input mounting flange, it may be necessary to fit stirrup mounts to the sides of the gearbox, see jbj Techniques' Pump Drive catalogue for details. When selecting either a single pump drive or a multiple power take-off, each of these factors must be considered. Failing to choose the right unit will lead to poor performance and an inefficient design, so ensure that you do your due diligence, and refer to all available resources, such as this selection guide from jbj Techniques Limited. By doing so, you can ensure that you choose the right unit for your particular needs.
Single pump drives or splitters? Understanding the pros and cons of each
Wondering if a single pump drive or a splitter gearbox (multiple power take-off) is right for your needs? It can be quite difficult to select the right pump drive for your needs. Here is a quick overview of the pros and cons of both single gearboxes and splitters.
Versatile and flexible: While splitter gearboxes are usually used to provide power from one prime mover to multiple drive units, they can also be used to unite the power provided by two different prime movers, and drive it into a single pump or other machine.
Allow multiple pumps or other devices to be driven with one prime mover: Splitter gearboxes allow for multiple pumps to be driven by a single prime mover with a high enough capacity. This includes gear pumps, vane pumps, screw pumps, and more. Of course, their usefulness is not only limited to pumps - they can drive a variety of other devices, such as water pumps, generators or connected with output drive shafts.
Typically more expensive: As you may expect, it's more expensive to purchase a two, three or four-way power take-off than it is to purchase a single output PTO gearbox.
More mechanically complex: Though only a single prime mover is required to drive multiple pumps, the PTO itself is more mechanically complex, and great care must be taken to choose the proper unit.
Simplified design: A single pump drive has a more simple design, as it is not designed to output power to more than one device. In some cases, this can also mean superior performance when driving a single pump, though this depends on the particulars of the application.
Comparatively inexpensive: Lower mechanical complexity means a lower overall cost of the unit, which can be a benefit in lower-budget projects.
Can't be used to unite multiple prime movers: This is one of the biggest drawbacks of a single pump drive. Being able to use one pump drive to accept power from multiple prime movers is very useful when designing and implementing projects.
Not ideal for parallel pumping: Parallel pumping is gaining acceptance in the world of hydraulics and plant design. It allows for less stress on each individual pump, and faster delivery of fluids via smaller pipes. Compared to multiple power take-offs, single pump drives are not ideal for parallel pumping.
Both single and multiple power take-offs have their own ideal applications - and it's up to you to decide which one may be right for your product, due to their unique advantages and disadvantages. However, jbj Techniques have the expertise to assist you and are happy to help!
This guide can help in choosing the right pump drive for an application. jbj Techniques has available a wide variety of single and multiple power take-offs and gearboxes - each of which can be used as a pump drive for many different tasks. Take a look at the guide now, and if you have questions about selecting the drive unit that's right for you, the company welcomes you getting in touch using firstname.lastname@example.org.