{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# 3 t b t c l chapter 13 gear trains 445 the table

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 5 ...(3 T B = T C) l Chapter 13 : Gear Trains 445 The table of motions is given below : Table 13.6. Table of motions. Revolutions of elements Step No. Conditions of motion Arm Compound gear B-C 0 Arm fixed , g ear A r otates through – 1 revolution (i .e . 1 rev. clockwise) 1. Gear A –1 + TA TB TA TB 2. Arm fixed, gear A r otates through – x revolutions 0 –x + x× 3. Add – y r evolutions to all elements –y –y Total motion –y –x–y + TA TB T × =+ A TB TD TD –y 4. Gear D x× TA –y TB + x× TA TD –y x× TA –y TD 1. Speed of arm when A makes 1 revolution clockwise and D makes half revolution anticlockwise Since the gear A makes 1 revolution clockwise, therefore from the fourth row of the table, – x – y = –1 or x+y=1 ...(i) Also, the gear D makes half revolution anticlockwise, therefore x× ∴ 1 TA –y= 2 TD 40 x – 90 y = 45 x× or x – 2.25 y = 1.125 From equations (i) and (ii), x = 1.04 ∴ 40 1 – y= 90 2 or and ...(ii) y = – 0.04 Speed of arm = – y = – (– 0.04) = + 0.04 = 0.04 revolution anticlockwise Ans. 2. Speed of arm when A makes 1 revolution clockwise and D is stationary Since the gear A makes 1 revolution clockwise, therefore from the fourth row of the table, –x –y =–1 or x+y=1 ...(iii) Also the gear D is stationary, therefore TA – y=0 TD or 40 x – 90 y = 0 or x× ∴ x× 40 – y=0 90 x – 2.25 y = 0 From equations (iii) and (iv), x = 0.692 ∴ and y = 0.308 Speed of arm = – y = – 0.308 = 0.308 revolution clockwise Ans. ...(iv) 446 l Theory of Machines Example 13.8. In an epicyclic gear train, the internal wheels A and B and compound wheels C and D rotate independently about axis O. The wheels E and F rotate on pins fixed to the arm G. E gears with A and C and F gears with B and D. All the wheels have the same module and the number of teeth are : TC = 28; TD = 26; T E = TF = 18. 1. Sketch the arrangement ; 2. Find the number of teeth on A and B ; 3. If the arm G makes 100 r.p.m. clockwise and A is fix...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online