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Saturday, 21 November 2015

HYDRAULIC JAW PULLER

Introduction

This Project is based on the study of a product or component for mechanical engineering applications. I have selected one quite important mechanical engineering component or product which plays a very important role in mechanical maintenance field for any industry.

I had a chance to visit one flagship organisation especially dealing in steel manufacturing sectors, I had studied there the various maintenance tools and devices those are normally used in that organization during mechanical maintenance in order to maintain the health of machinery in less down time.

I want to write here my personal experience with a very important mechanical device which is called by name as “Hydraulic puller”. I had seen two types of hydraulic puller in that organisation, first one the Hydraulic Jaw puller and second one is hydraulic Push puller. Both types of pullers could be used for maintenance activities.

Hydraulic puller is used for major activities, as mentioned below, in that organisation during mechanical maintenance.
  1. Removing bearing from shaft
  2. Removing Coupling from shaft
  3. Removing Gear from shaft
  4. Removing pulley from shaft
  5. Removing wheel from shaft
Hydraulic push puller and jaw puller could be seen in following figure and technical sketches also.
Figure 1, Hydraulic push and jaw Puller

Figure 2, Hydraulic puller (Push and Jaw Type)

I had discussed with the mechanical team and I had tried to accumulate some technical information’s about this important device which is assumed as very special and important tool for maintenance of respective equipment in that organization.

Hydraulic Puller: Technical information


I had noted the technical information of above device when maintenance team was removing Pulley and bearing.

Hydraulic Jaw puller

Capacity: 50 Ton
Reach: 730 mm
Spread: 800 mm
No. of jaw: 03

Hydraulic Push puller

Capacity: 50 Ton
Reach: 690 mm
Spread: 545 mm

Hydraulic puller operating principles

As we can see in above figure, there are various following components for hydraulic puller.
  • Sliding Plate
  • Hydraulic cylinder
  • Hydraulic inlet port
  • Pulling legs or jaw (in case jaw puller)
  • Pushing legs
Hydraulic puller as name indicates, it works one the hydraulic principle i.e. Pascal’s Law and we will have to use one hydraulic Pump in order to provide the required oil flow and pressure to the actuator (Cylinder) of hydraulic puller.

Let us consider the following figure and we will discuss the working of hydraulic puller here.

Figure 3, Hydraulic Jaw puller in application

As we can see, maintenance crew is trying to remove the pulley and coupling, in first part of figure and in second part of figure respectively, with the help of hydraulic jaw puller.

Inspection points

Before application of hydraulic jaw puller or push puller, we need to check following inspection point to complete the desired task.
  1. Oil level in hydraulic pump
  2. Release valve working or not
  3. Any leakage from hoses
  4. Pressure gauge is available or not with hydraulic pump
  5. Equipment is able to hold the pressure or not.
  6. Coupling or pulley dimensions, on the basis of outer diameter we will select the hydraulic puller as hydraulic puller spread must meet the outer diameter of that component which is going to be removed from shaft.
Now we will spread the jaw and fix the outer diameter of the coupling flange or pulley and simultaneously we will pump the hydraulic pump to feed the hydraulic oil in to the cylinder to extend the push rod in outward direction. 

We must have to note that push rod should be directed to the center of shaft. We will have to check the complete pulling unit once the push rod will touch the shaft center and we must have to check that pulling rod or jaw gripping with pulley or bearing or whatever component that we are going to remove from shaft.

Now we will pump again the hydraulic pump and push rod will move in outward direction and due to pushing action of push rod against shaft there will be pulling action by jaw or pulling rod.

Pulling rod or jaw is attached with the component, which need to be removed. Component will release its position and will move in forward direction. 

We will pump again the hydraulic pump to move the component, Coupling and pulley in above figure, and finally component will be removed from shaft without any extra effort and there will not be any damage mark over the surface of shaft and component (pulley and coupling) as we are removing the component by hydraulic pulling action with specified operation and maintenance procedure provided my manufacturer.

 

Figure 4, Pulling and pushing action

Once pulley or coupling will be removed from the shaft, we will release the pressure of hydraulic line by operating the release valve and push rod will move towards back side and will come to its original position. Hence, finally our task of removing coupling or pulley is completed successfully.

We will go ahead in our next post with new maintenance instrument i.e. Induction bearing heater

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