Hot tidbits

Titbits on engineering on methods of solving/testing/rectification evolved by any engineer/technician in his profession.

An early example of what this page is about was the titbits by one Mr. Marmaduke in American Power Magazine - he used to write about his practical problem solving on small ships on the high seas without much facility available readily on his ship. This used to be very good attraction for reading by engineers/technicians and follow up in many cases.

Contributions, please, from field engineers/technicians of today from any part of the world, in any language. Unlike a normal "article" page, this page welcomes authors' signatures.

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Remote operated garage door-opening

On one holiday one of my friends returned late in the evening with family and found that the garage door was not operating with the remote unit. What an embarrassing situation with family and friends waiting outside in the biting cold. They called an expert in that field and told him the problem. He just saw from the top of the garage door after some pushing it in, (of course by force), and put a thin but sufficiently rigid wire inside and pulled out something. Then he lifted the garage door manually from outside and opened the door.

He knew the trick of the trade by his long experience. Though it shows how foolish we were, we also thought how intelligent he should be.

Do not try this trick yourself. He did this trick since he knew the mechanism of the door working with his long years of experience.

If you study the system of its working you may understand what he did. Please be patient, study and think but do not try. You may damage the mechanism at an exorbitant cost to you.

--Dore chakravarty 06:06, 29 Nov 2005 (UTC)

A hammer blow made it all right

One of my senior engineers had kept his new home fridge ready packed for sending it to the repair shop in a far off place. The reason was the compressor recently refused to start but was tripping on overload. The compressor was fairly new and was under warranty.

On my seeing it I suggested that he uncover the packing at the back to expose the compressor body. There after I instructed him to give a blow on the compressor body by a wooden mallet with simultaneous switching on of the fridge. Maximum trial I said two should do. If the compressor starts with this trick he is lucky. If not it has to go back to repair shop only. But to his luck the compressor started and never gave trouble thereafter.

Do you know why this trick? Do not try this trick yourself please'

Can you guess how this trick worked?

--Dore chakravarty 21:45, 4 Dec 2005 (UTC)

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Why this trick on fridge?

In the early days the compressors in the home fridge were of two stage reciprocating type, driven by a common electric motor (not known today what is the construction). It was sealed in a domed container and installed at the back of the fridge to work as a sealed unit with evoparator, condenser, expansion valve etc.

The crank shaft of the compressor had a slight play in their bearings. Sometimes the crank shaft used to move slightly towards one bearing and get jammed. Hence is the non rotation and tripping on load when switched on. A slight tap on the sealed body of the compressor used to remove this jam and make the compressor free to rotate. Hence this trick, but not a positive one always.

--Dore chakravarty 19:04, 12 Dec 2005 (UTC)

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Deep bore well pump fallen inside bore. Trick to remove?

One of our deep bore well pumps had fallen inside the bore (about 600 feet deep) when the driving shaft at the top of pump body broke. The adjacent sketch

shows all the details.

Simple trick to recover the pump body.

The pump construction was such that it had a driving motor at the ground floor. This motor had a hollow shaft. The pump shaft coming out of the pump through this hollow shaft had a coupling at the top of the motor which also facilitated the impellor gap adjustment of the pump. The pump shaft had threaded coupling with casing pipes with bearings at intervals for the full length.

The pump shaft emerging at the top of the body had a threaded end. The trick was to make a suitable design of a long pipe with an end suitable for aligning and threading to the pump shaft to get attached to the pump.

The trick of the trade was fabrication of a fishing tool consisting of an inverted cone with a welded steel pipe coupling in the centre, at the end of the long pipe. This long pipe when lowered in the bore got automatically centered on the pump shaft. Turning the pipe at the ground floor did the trick of centering and threading the coupling of the cone on to the pump shaft. The pump was then taken out by withdrawing the full length of pipe.

--Dore chakravarty 04:33, 13 Dec 2005 (UTC)

How do you seal inert gas filled small size relays in your Industry lab after repair?

(See the answer here next week).

--Dore chakravarty 20:57, 17 Dec 2005 (UTC)

I got this trick by my observation years back in about 1945. A field photographer used only sensitised photo paper instead of plate or film in the plate holder. He got the negative first on the paper and developed it in a black box with flexible cloth arms to put his hand inside to take out the paper from the plate holder. The box had an opening with red glass to see inside while processing. He then developed the same in developer solution etc. and took a close up photo of the same to a get a positive photo on paper. He repeated the hand process and dried the paper in air. He then gave the photo to my father. (Even today, nearly after 60 years the photograph has still not faded).

I recently saw a photo of remote operation in an Atomic staion similar to the one above but more sophisticated.

This gave the clue to my repair of gas filled relays in my industry.

--Dore chakravarty 05:26, 1 Jan 2006 (UTC) --Dore chakravarty 17:48, 1 Jan 2006 (UTC)

Engineering at home!!

Please see next instalment!.

--Dore chakravarty 00:47, 13 Jan 2006 (UTC)

Our ancestors in South India used to sit on a wooden plank while taking food. While taking food static electricity is supposed to develop in the body for good digestion. This is assumed to be Gods’ creation. They never used to keep even their hand on ground at that time. This is to avoid any static electricity discharge to ground.

In the present day environment in urban areas almost every body uses dining table. Hence this concept is totally unknown.

--Dore chakravarty 21:35, 13 Jan 2006 (UTC)

How south Indian ladies check whether the hot plate on the stove has reached the required temperature (of course without thermometer) and is ready for Dosa making??

Please see next exciting instalment!.

--Dore chakravarty 21:35, 13 Jan 2006 (UTC)

Temperature without thermometer

+ How south Indian ladies check whether the hot plate on the stove has reached the required temperature (of course without thermometer) and is ready for Dosa making??

+ They just dip the end of their fingers in cold water and spray the water from wet fingures on the hot plate, kept hot on the stove. If the temperature is correct for dosa making dough to be poured on the plate then the water sprayed on the hot plate forms globules, move around and evoparate. The globules are formed because of steam formation around the water sprayed. If the temperature is lower than the requirement for making dosa then the the globules are not formed.

--Dore chakravarty 21:59, 9 February 2006 (UTC)

Removing Steam turbine blade deposits

+ Watch for this.

--Dore chakravarty 04:30, 14 March 2006 (UTC)

Use of Local workshop made injector hand held unit with cleaning powder of dry fly ash from precipitator hoppers would do the work. Since this powder is very abrasive many injectors have to be kept ready for use. Further any over cleaning does damage the blade surfaces and root. These are not desirable as tests have to be made with ultrasonic equipment and die testing kit for any cracks.

A box of about half cubic metre to be mounted above the work with a smooth connection tube of about 25mm.

Technocrat has to give a suitable design for injector fabrication.

The work enclosure must have suitable exhausting arrangement to remove the emanating dust.

The air pressure to injector can be through a pressure regulator suitably adjusted for outlet pressure.

The workman should wear all safety devices.

For turbine rotor see photograph at Steam_turbine

--Dore chakravarty 04:41, 17 March 2006 (UTC)

Two 500KVA diesel generator sets (with radiator cooling) in parallel - Problem

The two sets running independently gave the full output as per specifications. But when run in parallel one was getting overloaded even at 50% load with cooling water in the radiator boiling. Why is this problem?

On examination at site, the first thing was the examination of the neutral earthing done on both the units. This was done by them as per suppliers drawing for individual units. They had not given the scheme for the two working in parallel. The purchaser forgot the fundamental requirement that when two sets are run in parallel only one of them should be earthed. If both are earthed circulating current will flow between them through the earth connection. Generally a switch is provided in the earth connection so that any one can be earthed.

Then only one was earthed and run in parallel. Then both of them gave the rated output as per specification without any problem.

--Dore chakravarty 04:24, 20 March 2006 (UTC)

Re-entry vehicle of NASA command module early days- what was the heat shield?

Wait for the answer.

--Dore chakravarty 19:40, 20 March 2006 (UTC)

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The command module is the one which used to ferry the astronauts back to earth in early days of NASA.

Reentry condition

It's blunt edge will hit atmosphere at very high velocity while reentry. It becomes red hot for few seconds and then cools down due to reduced velocity during atmospheric flight. An observer on earth at that place can see the red hot reentry. The contact with astronauts was lost in those few seconds. The temperature inside for astronauts still remains at about 20°C.

Protection from heat

The blunt edge is provided with a honey comb type housing to a considerable depth and filled with some sort of wax.

Working

The wax like substance absorbs the heat energy due to conversion of kinetic energy, and melts. By the time the melting process gets deep inside the honey coumb housing it starts cooling down due to reduction in velocity during atmospheric flight. Thus the wax like substance will come back to its solid state again working like a heat shield.

Reference

Photo by NASA from book OUR WORK IN SPACE by National publishing house DELHI; INDIA, by Willy Ley, 1964.

--Dore chakravarty 23:16, 23 March 2006 (UTC)

Photo of command module red hot re-entry is shown now.[[1]]

--Dore chakravarty 20:11, 25 March 2006 (UTC)

Get away from the earth and never return (not myself of course)

You can. Imagine a mountain so high that the air no longer can interfere with the motion of the rocket fired from top of the mountain.

How?

Imagine a horizontal rocket launching site at the top.

Escape velocities

Note the ESCAPE VELOCITIES of the rocket.

First astronautical velocity or circular velocity;

It is 7.9 km per sec.

Second astronautical velocity or parabolic velocity or often termed velocity of escape.

It is 11.2 km per second.

Elliptical orbit.

It is between 7.9 and 11.2 km per sec.

Third astronomical velocity: to overcome both terrestrial and solar attractions.

It is not less than 16.7 km per sec

For further details see

Reference

Book INTERPLANETORY TRAVEL by A.STERNFELD (Second revised edition) (Winner of the International Encouragement , Prize in Astronatics, Published by FOREIGN LANGUAGES PUBLISHING HOUSE, MOSCOW 1958, (Tranaslated from the Russian by G.YANKOVSKY).

--Dore chakravarty 23:45, 25 March 2006 (UTC)

Engineers are often respected and ridiculed for their intense beliefs and interests.

Why??

Read Engineers_in_popular_culture

--Dore chakravarty 22:33, 7 April 2006 (PDT)

Computer System-does it replace human brain?? Read examples and comment.

See next week.

--Dore chakravarty 04:18, 12 August 2006 (UTC)

Examples

1. Automobile was giving little jerks at about 60km/hr.The authorised service station said no fault seen as per his computer diagnosis. When HT coil was replaced as per owner's request the above defect vanished. What about computer diagnosis??

2. Automobile radiator was getting empty after about 3 days. Authorised service station said no fault seen as per his computer diasgnosis. After examination by another experienced old mechanic, it was the failure of the radiator cap rubber washer which was not allowing the rated pressure build up in the cooling system. Why such defects are not incorporated in the diagnosis system of computer??

--Dore chakravarty 01:05, 21 August 2006 (UTC)

. (Please wait to see another automobile problem)

--Dore chakravarty 05:26, 18 May 2007 (UTC)

Automobile problem

I cam across an automobile about 10 years old. Every thing worked well. It started lately minute missed firing even at idle speed.

Thought that the problem could be in the ignition circuit only at the first instance. On careful visual checking of the ignition circuit it was found that the distributor rotor had a fine crack.

After replacement of this rotor the missed firing was not present.

--Dore chakravarty 07:31, 23 May 2007 (UTC)

Magnetic pick up tool

Do not throw away an old small speaker's magnet portion (it may be from your car or your music system) as it may be helpful at home, one time or the other.

It happened to me that one of my kitchen magnetic handle from a vessel fell down behind a kitchen cupboard. The cupboard was very deep at the back with no approach at all from the front.

A long length of strong thread was tied to the above small magnet and was lowered at the back of the cabinet holding the other end not allowing it to slip away from the hand.

When the magnet went down up to the level of the bottom of the cupboard and moved blindly, at one point, the vessel handle got attracted towards the magnet and got stuck to it. Some sound was heard and the weight was also felt on the thread. Then the thread was slowly withdrawn. The handle was found stuck to the magnet.

Thus the handle of the vessel was recovered.

One can preserve this magnetic pick up tool and improve it as well, to make it more reliable. This may be useful in all odd places like this, of course for magnetic materials such as screws, bolts etc.

Thinking of similar use of tool adoption may be necessary at times.

--Dore chakravarty 23:34, 19 July 2007 (UTC)

How to save on electricity bills?

Watch for the same.

--Dore chakravarty 05:11, 8 November 2007 (UTC)

One can save energy by using Compact Fluorescent Lights (CFL) and Light Emitting Diode (LED) bulbs as against the present incandescent or fluorescent lamps.

What are they.

CFLs can go into standard lamp sockets, and give off light that looks just like the common incandescent bulbs. LEDs are small, light bulbs which are extremely energy-efficient and there are many types. Some are without filaments. New LED bulbs are grouped together with some sort of diffuser in the front. This has already gone into use in portable torch lights.

Advantages.

Efficiency: CFLs are four times more efficient and last up to 8-10 times longer than incandescent lamps. A 22 watt CFL has about the same light output as a 100 watt incandescent lamp. CFLs use 50 to 75% less energy than incandescents.

Disadvantages.

CFLs are not to be viewed directly as the intensity is very high and harmful to the naked eyes.

Quality of Light.

Later CFLs give a warm light instead of the "cool white" light of older fluorescents. New CFLs using electronic ballasts do not flicker or hum.

Expenses and life.

CFLs are more expensive in the beginning. But CFLs last up to 10 times as long as incandescent lamps.

Saving.

You save money in the long run because CFLs use about fraction of electricity than incandescent.

Manufacture.

Even General Electric in USA, who are pioneers, have proposed stoppage of manufacture of incandescent lamps.

Others.

Even large and well established utilities like TVA in USA do recommend use of CFLs at homes.

Opinion sought.

The effect of Transmission lines near about the homes has still to be evaluated.

--Dore chakravarty 09:13, 6 January 2008 (UTC)

CFLs-Lightbulb-headache link rejected. A Christchurch manufacturer of energy-efficient light bulbs has dismissed British fears that the bulbs trigger crippling headaches.

Watch for further news in News items in News papers.

--Dore chakravarty 22:15, 6 January 2008 (UTC)

WIND MILLS IN DENMARK Recently there was a gale in the above country and it appears many wind mills were Destroyed. Please check up as Auckland(NZ) also proposing these.

--Dore chakravarty 05:07, 27 February 2008 (UTC)

IF YOU CARE FOR YOUR CAR THEN ONLY IT CARES FOR YOU

See how, shortly.

CARE FOR YOUR CAR

Do cars not stop on road sometimes? In a country like New Zealand, Automobile Association is there to help in that situation. But you have to wait on road stripping your ongoing programmes!. Is it not embarrassing?? What you can do to avoid such embarrassments? Though once in a way, it may happen.

READ THE BOOK

First of all read the book given with the car, such as owner’s manual, to know the full details of road side repairs.

WEEK ENDS

Every week end, if possible, do check the following.

Bonnet opening

1. Know first how to open bonnet of your car? Generally on the right side of the driver and underneath the dash board you have the provision to pull a liver. The bonnet pops out a little as it has one more catch to be handled manually, standing in front of the car. This double lock arrangement has been given for safety and is common in almost in all cars. Then put you fingers and move the latch (may vary from car to car and model to model) and lift the bonnet (generally heavy) and use the rod given and clamped at side of the engine, to keep the bonnet in the lifted position. This allows the engine to be examined in all aspects.

Spare wheel.

Check the boot of your car to see whether the spare wheel is available and the relevant spanners. See that jack and jack handle for replacing the wheels are also available. See also how to jack up the car at different wheels.

Battery.

(Generally not covered in service) This is one item which requires owners' attention. This may give trouble while starting the engine, particularly on cold days.

Terminals.

These, generally have been allowed to form sulphating, a sort of green colour deposit. Clean these deposits and smear vaseline on the terminals.

Topping up.

Some batteries are sealed ones and others are not. The later ones have to be topped up with distilled water (once in a way) after seeing the levels in each cell.

Jump start.

See that the jump cables are available in the boot. Some times you may have to use it rather than begging others. You know what it means to stop others.

Water in radiator.

The thermometer gauge provided for the driver indicates whether the engine is running hotter or normal. This has to be seen frequently while driving. If running hotter than normal, see whether water is upto correct level in the radiator bottle. The cap on the radiator is also to be examined for any lose or worn out gasket. If the water temperature shoots up, you are really in trouble. The engine may shatter and require replacement.

Other leakages.

See in general hoses and joints etc. for water leakages. Generally these are not common as they are covered under servicing.

Oil check.

Check the oil level in the brake bottle, the transmission bottle etc., as given in the book. These oil checks are normally carried out by the service guarage and they do a perfect job.

--Dore chakravarty 05:04, 11 March 2008 (UTC)