---
title: "Power shovel, backhoe and steel roller"
subject: "Construction Management"
chapter: 4
key: "semester_8/construction_management:power-shovel-backhoe-roller"
source: https://www.bctengineer.com/q/semester_8/construction_management/power-shovel-backhoe-roller
site: BCT Engineering
---

# Power shovel, backhoe and steel roller

Construction Management · Chapter 4: Familiarization with Construction Equipments

- Asked in: 2067 Mangsir (old course), 16 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/construction_management/power-shovel-backhoe-roller
- Whole chapter: https://www.bctengineer.com/md/semester_8/construction_management/chapter-4

## Question

Describe in detail the operation and application of the following types of excavating equipments with line diagram showing the basic parts: (i) Power shovel (ii) Back hoe (excavator) (iii) steel roller (3 wheeled).

## Short answer

A power shovel has a crawler base, revolving deck, boom, dipper and bottom-door bucket; it digs above track level and loads trucks in hard soil. A backhoe uses boom, stick and hydraulic bucket to dig below grade for trenches, foundations and basements. A three-wheel steel roller compacts granular sub-base and asphalt by repeated passes.

## Answer

#### (i) Power shovel (front shovel)
```text
            boom
          _/\_
        _/    \   dipper stick
   cab /       \__
 [____]         [bucket] digs upward/forward
 [=tracks=]
```
Basic parts: crawler base, revolving deck with cab and engine, boom, dipper (stick), and bucket with a hinged bottom door.
**Operation:** the bucket is crowded forward into the bank and lifted upward, curling in material; the machine swings, and the door is opened to dump into a truck.
**Application:** digging above the track level (hillside, borrow pits, quarry), loading trucks, in hard and rocky soil with high output (bucket 1-5 m$^3$). It is not suitable for digging below its own level or for wet ground.

#### (ii) Backhoe (hydraulic excavator)
```text
           boom
        __/\___ stick
       /        \
 [cab]/          \__bucket (teeth face machine)
 [==tracks==]
```
Parts: undercarriage (tracks or wheels), swing platform, boom, stick, bucket, hydraulic cylinders.
**Operation:** the boom is lowered, the bucket is extended out and pulled toward the machine to dig; it is curled, lifted, swung and dumped.
**Application:** trenches for pipes and cables, foundation pits, basement excavation, below-grade digging, ditches, demolition and loading trucks. Its 360-degree swing and precise control make it the most common site excavator.

#### (iii) Three-wheel steel roller
```text
      [seat]
   ___|_____|___
  (   ) front guide wheel (steel drum)
   (  rear drive wheels - two big steel drums )
```
Parts: one front steering drum and two large rear drive drums, engine, frame, water spray and scrapers, ballast.
**Operation:** it makes repeated passes at 3-6 km/h, with overlap, from the edges toward the centre; the weight is 8-12 t (ballast can be added).
**Application:** compaction of granular sub-base, base course and macadam, initial rolling of asphalt, giving a smooth surface. Not suited to cohesive soils for deep compaction.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Where does a power shovel dig?
   A. Above track level, such as hillside and quarry
   B. Below the machine in wet ground
   C. Only trenches
   D. Only underwater
   Answer: A. A power shovel digs above its track level. (Key point: Power shovel digging level)

2. How does a power shovel dump?
   A. The bucket is dragged
   B. Tilted by hand
   C. Sucked by pump
   D. A hinged bottom door of the bucket opens
   Answer: D. The bucket has a hinged bottom door that opens over the truck. (Key point: Shovel dumping)

3. How does a backhoe dig?
   A. Rope thrown
   B. Rotating cutter
   C. Bucket extended and pulled toward the machine, curled, lifted, swung and dumped
   D. Bucket pushed upward into the bank
   Answer: C. A backhoe pulls toward the machine to dig below grade. (Key point: Backhoe action)

4. What is the layout of a 3-wheel steel roller?
   A. Two front drums and one rear
   B. One front steering drum and two large rear drive drums
   C. Three equal tyres
   D. Three feet drums
   Answer: B. It has one front steering drum and two rear drive drums. (Key point: Three-wheel roller)

5. Where is a 3-wheel steel roller suited?
   A. Granular sub-base, base course, macadam and initial asphalt rolling
   B. Deep clay compaction
   C. Digging
   D. Hauling
   Answer: A. It suits granular layers and asphalt; not deep cohesive compaction. (Key point: Roller application)

## Related in Construction Management

- [Road construction equipment, paver and bitumen sprayer](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Aroad-equipment-paver-sprayer) — Construction Management, chapter 4
- [Contractor cash flow estimate and critical stage](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Acontractor-cash-flow-estimate) — Construction Management, chapter 6, asked 2×
- [Inventory planning and ABC classes from data](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Aabc-table-inventory-2077) — Construction Management, chapter 3
- [Front-end loader and dragline](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Afront-end-loader-dragline) — Construction Management, chapter 4
- [Art and science of writing specifications](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Aspec-art-science-writing) — Construction Management, chapter 12
- [When cost, plinth area, development methods apply](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Avaluation-methods-situations) — Construction Management, chapter 13

## Related in other subjects

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- [MBI block diagram and basic features](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-block-features) — Instrumentation II, chapter 1, asked 4×
- [Shield's diagram and its application](https://www.bctengineer.com/question.md?key=semester_4%2Fhydraulics%3Ashield-diagram-application-design) — Hydraulics, chapter 10, asked 5×
- [Stress-strain diagram for mild steel](https://www.bctengineer.com/question.md?key=semester_3%2Fstrength_of_materials%3Astress-strain-diagram-mild-steel) — Strength of Materials, chapter 3