Question

What is the function of (a) press plunger and (b) pump plunger in a hydraulic press ?

Answer 1

Principle. A hydraulic press is a hydraulic machine based on Pascal's law.

Design/construction. A schematic diagram of a hydraulic press is shown in Fig.

It consists of the following parts/components.

1. Two hollow cylinders A and B, fitted with valves V₁ and V₂ at their bottom.
2. Cylinder A is narrow, whereas cylinder B has much larger area of cross-section.
3. The two cylinders are connected to each other with the help of a strong metallic pipe.
4. Cylinder A is connected to a water tank through a pipe and valve Vi
5. Both the cylinders are fitted with watertight pistons (P, and P₂).
6. Piston P, is smaller in size and is called pump plunger, whereas piston P₂ is larger and is called press plunger or rain-cylinder
7. The piston P₁ (in cylinder A) can be operated with the help of a lever arrangement and a handle.
8. Cylinder B is connected to the water tank through a release valve in its lower portion.
   Cylinder B is connected to the water tank through a release valve in its lower portion.
9. The top of the ram (or press plunger) forms a platform to keep the material compressed.

Working. The hydraulic press operates as follows:

1. When the pump plunger (Piston P₁) is raised by raising the handle, the pressure inside cylinder A decreases, the valve V, opens upwards and water from the tank enters the cylinder.
2. When the pump plunger is lowered by lowering the handle, the valve V₁ closes and the pressure is transmitted to the liquid in a pipe. This pushes open valve V, and the water from cylinder A enters cylinder B.
3. The water entering cylinder B pushes the press plunger upwards and the material to be compressed such as cotton gets compressed such as , cotton gets compressed.
4. To bring the press plunger back, the release valve is opened. This allows water to run into the tank from cylinder B.