Backhoe Loader Hydraulic: The Heart of Machine

The backhoe loader is a simply amazing machine that can very easily dig a 10 feet long and 5 feet wide in under 15 minutes. A task that if done manually would have taken hours to get done. That being said lets take a look into what exactly makes this incredible machine so fast and effective.

It is a well known fact that a backhoe loader uses hydraulics to do all the heavy lifting. A hydraulic system is basically an arrangement that uses an incompressible fluid, usually oil to transmit force from one point to another. And given that the fluid is incompressible, almost all of the force is transferred unlike other systems where there is some loss of the transferred force.

The two variables at work here are distance and force. Operating the backhoe is a dance to balance both the variables to get the desired results. The work done on pressing down a piston on the left has the two variables as to how much force is being applied and how far the piston is being pushed. Pushing down on the left in turn pushes a certain amount of fluid. Now since the fluid is incompressible, all the force is transferred and so the piston on the right is pushed forward.

The pressure across the system remains the same. The pressure on the piston on the right is working on a larger area meaning it will push upward with greater force. Lets take an example for better understanding.

Left piston has a say 2 inch diameter

Right piston has a say 6 inch diameter

If one were to calculate the area of each piston, we would realise that the piston on the right has an area 9 times that of the left. Simply put, the force applied on the left piston will result in 9 times the force on the right piston. Or it would require the left piston to be moved 9 inches for the right one to be moved an inch. This is hydraulics at its simplest.

While the principle remains the same, a backhoe loader needs to be working continuously and thereby requires constant oil pressure. This is achieved by a oil pump that is powered by a rather powerful diesel engine. The pump keeps a constant supply high pressure going into the valve block system from where the force is then directed further. The pump works like the narrow piston in the above example, it applies a slight force with great speed in turn moving the other piston slowly but with a greater force.

The above mentioned simple system however isnt good enough for a backhoe loader since the pistons need to be able to both push and pull. A piston system called a hydraulic ram is used in a backhoe loader. The ram is fed by hose on both ends letting the piston move in both directions as required by applying pressure from the required end.

A spool valve is used to help the piston move in two directions. The pump pushes oil taken from the tank to the spool valve through the hoses.When the operator changes the direction , the configuration of the spool valve changes accordingly. High pressure oil is pumped in from one direction and low pressure oil pulled back into the tank from the other end.

These days the backhoe loaders are equipped with variable displacement pumps. These make is possible to reduce wastage of energy and fuel. This small addition to the hydraulics ensures that oil is not pumped unless a load is sensed. While a small addition to the hydraulic arrangement, it helps increase fuel efficiency by 7-8percentage. Hydraulics combined with smart electronic circuits make the machine as a whole more efficient and easier to operate. The hydraulics are powered by some of the most powerful diesel engines available in the market today that make these machines worth every penny spent on them.

Operators use the joysticks to operate the pistons and in turn control the movement of the spool valve. It is with the manipulation of these hydraulic pistons by the joysticks that the operators manage to complete seemingly difficult tasks with ease. Simply put it is these hydraulic systems that make the heart of these mean machines.