3D printing construction can be among the main construction technologies February 2019
Engineer Jagvir Goyal tells us what makes the backhoe loader tick.
Just like a photocopier is better known as a 'Xerox' machine, the backhoe loader is known to many simply as a JCB. Invented by JCB founder JC Bamford about 55 years ago, the backhoe loader is now available from other companies too, although JCB continues to be a market leader.
Though hydraulic excavators and front loaders are preferred equipment among construction managers, backhoe loaders remain in demand for their two-in-one ability and versatility. They can do multiple jobs and prove useful when jobs are smaller in magnitude but urgent in nature. Under such circumstances, it is uneconomical and difficult to transport heavy earthmoving machinery. Backhoe loaders can handle the work of dozing, loading, back filling, excavating, scrapping, grabbing and grading a site effectively. They can be used for foundations for buildings, pipeline excavations, channel digging and cleaning, and handling of materials like soil and aggregate. Backhoe loaders can also be dubbed 'city equipment', ideal for municipal corporations to keep handy for multiple jobs. Tyre-mounted backhoe loaders can easily move in and around a city for various construction and maintenance-related jobs.
A backhoe loader basically has a loader and an excavating arm attached to a tractor. On the front, it has a loader bucket and, on the back, a boom, an arm pivoted to the boom called a dipper and a bucket attached to the dipper for excavation work. The tractor can be either trailer or tyre-mounted. In case of tyre mounted backhoes, the number of tyres can be two or four. The type of tyres to be used can be chosen depending upon the type of ground to be traversed by the backhoe loader.
A backhoe loader is really useful only if its multiple attachments are kept available and the arrangement provided to change the attachment to the dipper or loader arm is instant and easy. With this in mind, manufacturers are devising multiple attachments to increase the utility of backhoe loaders, as follows:
Shovels: Different shapes are provided to handle loose materials.
Side-tip shovels: These are provided to stack loose material on the side instead of in front. They can unload material both on the left or right, as required and tip sideways instead of front unloading.
Snowblades: These can be fitted to the loader's arms and remove snow through rotary action. The power supply to these blades is independent. They have blowers attached to them to direct loose snow away from the machine
Forks: Forks of different lengths can be attached to backhoe loaders to forklift, unload and stack different materials.
Clam shovels: In addition to normal shovels, hydraulically operated clam shovels can be attached to backhoe loaders for grabbing, loading, backfilling, dozing, excavation, etc.
Sweepers: These are large, hydraulically operated brushes. They can be attached to the loader's arms and used effectively and efficiently to sweep clean roads, sites, store yards, tracks and other similar places.
Pole handlers: These can carry poles, position them and place them for easy erection at site. These are useful for handling poles for power and telecom lines.
Excavation buckets: Many types and sizes of excavation buckets with hardened teeth can be attached to the rear arms of the loader for excavation work.
Hammers and breakers: Instead of excavation buckets, hammers and breakers can be mounted on the dipper arms at the back. These have independent source of power and can break road surfaces or even rocks quickly.
Hedge trimmers and grass mowers: These can be attached to the backhoe loader to trim hedges or mow grass along the roadside.
Spreaders: A plastic hopper can be mounted on the backhoe loader. Through this hopper, materials like grit or fertilisers can be spread evenly. This attachment by JCB has added more versatility to backhoe loaders.
Finishing mowers: These can be attached to the back for even mowing of green areas. They have a three-blade attachment to achieve desired finish.
Silt removers: These can be attached to the back of the backhoe loader and prove useful in removing silt and weed in waterways.
Drilling augers: They can be attached to the back of the backhoe loader and can drill 6 inch to 3 ft diameter holes in the ground up to a depth of about 2 m. They prove very useful in erection of poles and posts and enhance the speed of work on roadsides or areas where it is difficult for the crew to continuously shift excavation tools.
Compactor plates: These are hydraulically operated compactors that can be used on surfaces or trenches through an attachment on the back of the backhoe loader.
Kerb masters: These special attachments on the back of the backhoe loader help position road kerbs. They can be manually or hydraulically operated.
Drain makers: These are special buckets attached to the back of the backhoe loader. Most drains have tapered sides. To facilitate their shaping, drain maker buckets have one side tapered, either 30° or 60°.
Lifting hooks: These can be attached to the dipper arm at the back and are useful in lifting pipes, girders or other materials at site. The capacity varies from 1 tonne to 2 tonne.
Ripper tooth: A special type of ripper tooth bucket can be attached to the rear end of the backhoe loader. This is useful in ripping road surfaces.
Many manufacturers around the globe produce many models of backhoe loaders these days. Most vary in size, operating weight, capacity, engine power and attachments, with other basic features remaining the same. The following important features should be checked while buying or hiring a backhoe loader:
1. The length of the boom and dipper or the articulated arm will tell you the reach of the backhoe loader. These should preferably be equal. Their sections should be strong but small. Small sections will enhance operator visibility. The dipper should be telescopic.
2. Boom slewing angle should be more than 180° to allow the boom to slew left and right for maximum efficiency.
3. Chassis should be a one-piece structure with higher ground clearance and bigger capacity fuel tank.
4. The engine should be powerful and efficient with auto transmission.
5. The backhoe loader should be able to travel uphill easily. Road travel speed should be fast, with the ability to reach 40 km per hour.
6. Hydraulic hoses provided in the backhoe loader should not be prone to damage during operation.
7. Operator cabin should preferably be air-conditioned and noise-proof, with excellent all-round visibility, comfortable high-level seats and low-effort knobs and buttons. During winter, the cabin should have a pre-heating option without running the engine. This creates a better working environment for the operator and demists the cabin.
8.Maximum attachments should be available.
9. Whenever the backhoe loader is switched to digging, the shovel should automatically set itself to digging position.
10. A four or two-wheeled backhoe loader can be chosen according to your requirement. The option of using different types of tyres with respect to the ground to be traversed should be available.
11. The service period spans should be large. This allows better usage hours and lower maintenance costs.
12. The cabin should have indicators or sensors for water, fuel and air filter status.
13. The backhoe loader should provide easy and instant access to critical points for inspection, cleaning and changing oils. The air cleaner, greasing points, engine oil drain plug and radiator are among these critical points. The radiator often needs cleaning owing to the continuous working of the backhoe loader at sites and clogging from dirt. It should be easy to replace or maintain.
A backhoe loader can be converted into a front loader simply by detaching the excavation arm. The arm of the excavator attached to the tractor and known as the boom as well as the slew arm attached to the boom through a pivot joint and known as the dipper along with the bucket attached to the dipper can all altogether be removed and kept aside in case they are absolutely not required on site or if there are space constraints. Sometimes, the backhoe loader is positioned at a higher level and the boom and dipper arms are not able to excavate at a low level despite full stretching of arms. In such circumstances, another dipper arm can be added to the dipper. This arm can increase the reach of the backhoe loader by 4-5 ft. The additional dipper arm is independently powered.
Among the safety features of backhoe loaders, the most important are an efficient brake system and hydraulic system for the loader and excavator. The brakes should be multi-disc type, fully sealed against entry of dirt with a high service life. These should apply to all four wheels of the loader and should be effective even under slippery conditions. In addition, a parking brake should be available to the operator to use in case the brakes don't work owing to some fault like failure of oil supply. Third, an alarm system should be available in the loader to warn the operator in case of any emergency or abnormality. The access system to the backhoe loader has to be easy, with the stairways provided with handrails.
JCB, the inventor of backhoes, occupies the top position among manufacturers though CAT, Volvo and other competitors also produce many models. JCB produces 18 models of backhoes. The basic configuration is 1CX, 2CX, 3CX and 4CX. Under each configuration, different varieties are available to choose a backhoe loader according to site requirements. The basic ICX backhoe loader operates at 50 hp, has an operating weight of 2,790 kg and a digging depth reach of 2.55 m. Its variant MIDI CX has a digging depth of 3.05 m. The biggest JCB backhoe loader model is the 4CX Super SM with engine power of 100 hp, operating weight of 8,880 kg and digging depth capacity of 4.98 to 6.14 m.
JCB has invented a 'torquelock' feature in its backhoe loaders. This reduces fuel consumption by 25 per cent, increases speed and working radius by 10 per cent and increases working area by 20 per cent. Another feature, hydraulic speed control (HSC), cuts off the hydraulic pump when the backhoe loader is simply travelling. This cuts fuel consumption. JCB's 'extradig' feature allows you to dig further away from the loader as well as closer to the loader. JCB's 4CN model has an additional 30° articulation that allows lesser repositioning, thus saving time and increasing output. During loading jobs, the transmission system directs hydraulic power to the loader for quick lifting. JCB's 3CX, 4CX and 4CN backhoe loaders are equipped with Dieselmax engine, described by JCB as a ‘breathtaking innovation’. This engine is claimed to be the world's fastest working diesel engine that provides high torque at low revolutions.
For its part, Caterpillar, known as CAT, produces four models of backhoe loaders. They can travel at 40 kph; are equipped with a wide range of attachments like hammers, augers and compactors; have spacious operator cabins; and are provided with an integrated tool carrier option with quick change facility for blades, buckets, brooms or forks. The hydraulic system is quite powerful and of the load sensing type. Its variable displacement piston pump and valves sense the load and regulate flow and pressure accordingly. This system not only keeps the hydraulic system cool but increases fuel efficiency and reduces wear and tear and noise. CAT backhoe loaders include the 416E, 420E, 430E and 450E models. The lowest model 416E runs with an 87 hp net power engine while the largest, 450E, runs at 124 hp net power. Dig depth varies between 14 ft and 17 ft. The booms are excavator style with narrow box section of thicker plates, thus enhancing durability and visibility. The curved design helps overcome obstacles during loading and digging.
Meanwhile, Volvo has two models of backhoe loaders: BL60 and BL70. The BL60 model operates at 83 hp and the BL70 model at 90 hp. The maximum speed is 34 kmph with lifting capacity of 3.3 tonne. The boom has a curved design and the diesel engine is Volvo D5D make. The BL60 model also has the same engine with a slightly higher travel speed and lower lifting capacity. Other major producers of backhoe loaders are Liebherr, Komatsu, Terex and Hitachi.
• Backhoe loaders continue to be in demand due to their two-in-one ability and versatility.
• The length of the boom and dipper or the articulated arm should be equal.
• The brakes of backhoe loaders should be multi-disc type and should apply to all four wheels of the loader.
About the author:
JAGVIR GOYAL authors technical books and is a columnist for technical journals. He is Director Estates, PSEB, Punjab, Deputy Chief Engineer (Civil) and recipient of the TIET Distinguished Alumni Award 2005. He can be contacted at email@example.com