Shaft Couplings

Given: Detail (part) drawings of an Unprotected Flange Coupling as shown in Fig. 6.8.

Scale: 1:1 (Full Size)

Parts Identified in an Unprotected Flange Coupling:
1. Flange A (with hub, flange disc, bolt holes, keyway)
2. Flange B (with hub, flange disc, bolt holes, spigot/socket recess, keyway)
3. Shaft A
4. Shaft B
5. Key A (Rectangular Sunk Key)
6. Key B (Rectangular Sunk Key)
7. Bolts, Nuts and Washers (typically 3 or 4 sets)

Assembly Procedure (Step-by-Step):

Step 1 – Understand the assembly:
- The two shafts (Shaft A and Shaft B) are to be coupled end-to-end.
- Flange A is fitted on Shaft A using Key A; Flange B is fitted on Shaft B using Key B.
- The two flanges are brought face-to-face; the spigot of one flange fits into the socket (recess) of the other for alignment.
- Bolts pass through the bolt holes in both flanges and are secured with nuts and washers.

Step 2 – Draw the Front View (Upper Half in Section):
- Draw the horizontal axis (shaft centre line) as a chain-dot line.
- Draw the two shafts as rectangles (diameter as given, e.g., $\phi 40$ mm) extending from both sides.
- Draw the hubs of Flange A and Flange B around the respective shafts.
- Show the keyways on the shafts and in the hubs in the sectional half.
- Draw the flange discs of both flanges meeting at the centre.
- Show the spigot (projection) of one flange fitting into the socket (recess) of the other.
- In the upper half (above the centre line): draw the section — apply hatching (thin lines at $45°$) to all cut solid parts (hub, flange disc, shaft cross-section). Bolts passing through bolt holes are not hatched (bolts are not sectioned by convention).
- In the lower half (below the centre line): draw the external (outside) view — show the bolt heads/nuts, the outer profile of flanges and hubs.
- Show all important dimensions: shaft diameter, hub diameter, hub length, flange diameter, flange thickness, bolt circle diameter (PCD), bolt diameter, number of bolts, overall length, keyway dimensions.

Step 3 – Draw the Right Hand Side View (Without Section):
- Project from the front view to the right.
- This view shows the right-side face of Flange B (or Flange A depending on orientation).
- Draw the outer circle of the flange disc.
- Draw the bolt holes (as circles) equally spaced on the pitch circle diameter (PCD).
- Draw the hub circle (concentric).
- Draw the shaft circle (innermost concentric circle).
- Show the nuts (hexagonal or square) on the bolt ends if visible.
- Show centre lines for all circles.
- No hatching (no section in this view).

Step 4 – Dimensioning:
- Dimension all diameters with the $\phi$ symbol: shaft $\phi$, hub outer $\phi$, flange outer $\phi$, bolt circle $\phi$, bolt hole $\phi$.
- Dimension lengths: hub length, flange thickness, overall coupling length.
- Dimension keyway: width $\times$ depth.
- Use leader lines and dimension lines as per SP:46 conventions.

Step 5 – Title Block and Projection Symbol:
- Write Title: ASSEMBLY OF UNPROTECTED FLANGE COUPLING
- Write Scale: 1:1
- Draw the First Angle Projection Symbol (frustum of cone — as used in CBSE/Indian standard) in the title block.

Key Conventions to Follow:
- Centre lines: thin chain-dot lines.
- Cutting plane line shown on the front view.
- Section lines (hatching) at $45°$, equally spaced ($\approx 3$ mm apart).
- Bolts, keys, shafts — not sectioned even if the cutting plane passes through them.
- Hidden lines may be omitted in the sectional view for clarity.

Result: The assembled orthographic views of the Unprotected Flange Coupling are drawn to scale 1:1 with the front view (upper half in section) and the right-hand side view (without section), fully dimensioned with title and projection symbol.

Given: Detail drawings of an Unprotected Flange Coupling — Fig. 6.9.

Scale: 1:1

Parts of Unprotected Flange Coupling:
1. Flange A (with hub and keyway)
2. Flange B (with hub, spigot/socket, and keyway)
3. Shaft A and Shaft B
4. Key A and Key B (Rectangular Sunk Keys)
5. Bolts, Nuts, Washers

Assembly Steps:

Step 1 – Fit keys and flanges on shafts:
- Insert Key A into the keyway of Shaft A; slide Flange A onto Shaft A so that the keyway of the hub aligns with Key A.
- Similarly, fit Key B and Flange B onto Shaft B.
- The flanges are positioned so that the flange faces are flush with the shaft ends.

Step 2 – Couple the flanges:
- Bring Shaft A and Shaft B coaxially together.
- The spigot (male projection) on Flange B enters the socket (female recess) on Flange A for accurate alignment.
- Align the bolt holes of both flanges.
- Insert bolts through the holes; place washers and tighten nuts.

Step 3 – Draw Front View (Lower Half in Section):
- Draw the horizontal axis as a centre line.
- Draw both shafts, hubs, and flange discs symmetrically about the axis.
- Lower half (below centre line): Show the section — hatch all solid cut parts (shaft, hub, flange disc) at $45°$. Do NOT hatch bolts, keys, or nuts.
- Upper half (above centre line): Show the external view — outer profiles of flanges, bolt heads/nuts visible.
- Show spigot-socket fit at the mating face.
- Dimension: shaft $\phi$, hub $\phi$, hub length, flange $\phi$, flange thickness, PCD of bolts, bolt $\phi$, keyway size, overall length.

Step 4 – Draw Right Side View:
- Project from the right end of the front view.
- Draw concentric circles: shaft circle (innermost), hub circle, bolt hole circles on PCD, flange outer circle.
- Show bolt holes (usually 3 or 4) equally spaced on the PCD.
- Show nuts (hexagonal) if visible.
- Mark all centre lines.
- No section in this view.

Step 5 – Title and Symbol:
- Title: ASSEMBLY OF UNPROTECTED FLANGE COUPLING
- Scale: 1:1
- Draw First Angle Projection Symbol.

Result: Assembly drawing of Unprotected Flange Coupling drawn to scale 1:1 with front view (lower half in section) and right side view, with all dimensions, title, and projection symbol.

Given: Assembly drawing of an Unprotected Flange Coupling.
Task: Extract (disassemble) individual parts and draw their detail views.
Scale: 1:1 (Full Size)

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(a) FLANGE-A

Description of Flange-A:
Flange-A consists of a cylindrical hub (with a central bore equal to shaft diameter and a keyway), and a circular flange disc with bolt holes. It may have a socket (recess) for the spigot of Flange-B.

(i) Upper Half Sectional Front View of Flange-A:

Step 1: Draw the horizontal centre line (axis of the bore).

Step 2 – Lower half (external view):
- Draw the outer profile: hub cylinder and flange disc as rectangles.
- Show the outer diameter of the hub and flange disc.
- Show the length of the hub.
- Show the socket recess (if present) on the face of the flange.

Step 3 – Upper half (sectional view):
- The cutting plane passes through the axis.
- Show the bore (shaft hole) through the hub — draw as a rectangle equal to shaft diameter.
- Show the keyway: a small rectangular notch at the top of the bore.
$$\text{Keyway width} = b, \quad \text{Keyway depth} = d$$
- Show the bolt holes in the flange disc (as rectangles in section).
- Show the socket recess depth and diameter.
- Apply hatching at $45°$ to all solid cut material.
- Do NOT hatch the bore (empty space) or keyway.

Step 4 – Dimensions to show:
- Bore diameter $\phi$ (= shaft diameter)
- Hub outer diameter $\phi$
- Hub length
- Flange outer diameter $\phi$
- Flange thickness
- Bolt hole diameter $\phi$ and PCD
- Keyway: width $\times$ depth
- Socket recess: diameter $\phi$ and depth

(ii) Right-Hand Side View of Flange-A:

Step 1: Project from the right side of the front view.

Step 2: Draw concentric circles:
- Innermost: bore circle ($\phi$ = shaft diameter)
- Next: hub outer circle
- Bolt holes: small circles equally spaced on PCD circle
- Outermost: flange outer circle

Step 3: Show the keyway as a small rectangle (chord) inside the bore circle.

Step 4: Draw all centre lines (horizontal, vertical, and radial to bolt holes).

Step 5: Dimension: all diameters, PCD, number and diameter of bolt holes.

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(b) KEY-A (Rectangular Sunk Key)

Description: A rectangular sunk key is a simple rectangular prism with uniform cross-section. It fits half in the shaft keyway and half in the hub keyway.

Let: Length $= L$, Width $= b$, Height (thickness) $= h$

(i) Front View of Key-A:
- The front view shows the key as a rectangle.
- Width of rectangle $= L$ (length of key), Height of rectangle $= h$ (thickness of key).
- Draw with thin lines; show dimensions $L$ and $h$.
$$\text{Front View: Rectangle of size } L \times h$$

(ii) Top View of Key-A:
- The top view shows the key as a rectangle.
- Width $= L$ (length), Depth $= b$ (width of key).
$$\text{Top View: Rectangle of size } L \times b$$
- Draw directly below the front view with projection lines.

(iii) Left-Hand Side View of Key-A:
- The LH side view shows the cross-section of the key.
- It appears as a rectangle of size $b \times h$ (width $\times$ thickness).
$$\text{LH Side View: Rectangle of size } b \times h$$
- Draw to the left of the front view with projection lines.

Dimensions to mark:
- On Front View: $L$ (length) and $h$ (height/thickness)
- On Top View: $b$ (width)
- On Side View: $b$ and $h$ (for confirmation)

Title Block:
- Title: DETAIL DRAWING — UNPROTECTED FLANGE COUPLING
- Parts: FLANGE-A, KEY-A
- Scale: 1:1
- Draw First Angle Projection Symbol.

Given: Assembly drawing of Unprotected Flange Coupling — Fig. 6.12.
Task: Disassemble and draw detail views of Flange-A and Hexagonal Nut.
Scale: 1:1

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(a) FLANGE-A

(i) Front View — Lower Half in Section:

Step 1: Draw the horizontal axis (centre line of bore).

Step 2 – Upper half (external view, above centre line):
- Draw the outer profile of the hub (cylinder) and flange disc.
- Show the face of the flange with the socket recess (if present).
- Show the outer contour lines of hub and flange.

Step 3 – Lower half (sectional view, below centre line):
- The cutting plane passes through the axis.
- Show the bore (shaft hole) as a rectangle.
- Show the keyway as a small rectangular notch at the bottom of the bore.
- Show the bolt holes in the flange disc as rectangles.
- Show the socket recess (depth and diameter) if present.
- Apply hatching ($45°$, equally spaced) to all solid cut material in the lower half.
- Do not hatch the bore or keyway (these are empty spaces).

Step 4 – Dimensions:
- Bore $\phi$, Hub outer $\phi$, Hub length
- Flange outer $\phi$, Flange thickness
- Bolt hole $\phi$, PCD of bolt holes
- Keyway: width $\times$ depth
- Socket recess: $\phi$ and depth

(ii) Side View — Looking from Left:

Step 1: Project from the left side of the front view.

Step 2: Draw concentric circles:
- Bore circle (innermost)
- Hub outer circle
- Bolt hole circles on PCD
- Flange outer circle (outermost)

Step 3: Show the keyway as a small rectangular notch inside the bore circle (at the appropriate position — bottom, since lower half was sectioned, keyway is at bottom).

Step 4: Show all centre lines.

Step 5: Dimension all diameters and PCD.

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(b) HEXAGONAL NUT

Description: A standard hexagonal nut has a hexagonal prism body with a threaded central hole. The top and bottom faces are flat; the top corners are chamfered (giving a curved profile on the front view).

Let: Nominal diameter of bolt $= d$
- Across flats (width across flats): $W = 1.5d + 3$ mm (approx.) or as given
- Thickness of nut: $T \approx 0.8d$ (approx.) or as given
- Chamfer circle diameter $\approx W$ (across flats)

(i) Front View of Hexagonal Nut:

Step 1: Draw the rectangle of width $= W$ (across flats) and height $= T$ (thickness).

Step 2: Show two vertical lines inside the rectangle at positions corresponding to the two visible corners of the hexagon (at distance $=$ across corners $/2$ from centre).

Step 3: Draw the chamfer arcs:
- The chamfer on the top corners produces hyperbolic curves; for drawing purposes, these are approximated as arcs of circles.
- Draw arcs from the top corners curving inward to meet the vertical edge lines.
- The arc radius $R = W$ (across flats) approximately.

Step 4: Show the threaded hole:
- Draw two vertical lines (representing the thread) inside, at diameter $= d$ (minor diameter shown as thin lines, major diameter as thick lines).
- Alternatively, show as two thin lines for the thread representation.

Step 5: Dimension: $W$ (across flats), $T$ (thickness), $d$ (nominal diameter).

(ii) Side View of Hexagonal Nut:

Step 1: Project from the right (or left) of the front view.

Step 2: In the side view, the hexagon appears with two corners pointing left and right (if the front view shows flats).
- Draw the hexagon: it will show as a rectangle of width $=$ across corners and height $= T$, with two angled lines on left and right sides.

Step 3: Show the chamfer arc on top.

Step 4: Show the threaded hole as a circle of diameter $d$ (with a gap/break in the circle to indicate thread — thin circle for minor diameter, thick circle for major diameter).

Step 5: Dimension: across corners dimension, thickness $T$.

Title Block:
- Title: DETAIL DRAWING — UNPROTECTED FLANGE COUPLING
- Parts: FLANGE-A, HEXAGONAL NUT
- Scale: 1:1
- Draw First Angle Projection Symbol.