Chapter 6 VEHICLE SELECTION. STUDY OBJECTIVES At the end of this chapter students will be expected...

Chapter 6

VEHICLE SELECTION

STUDY OBJECTIVES

At the end of this chapter students will be expected to:Discuss the role of vehicle selection and design in

terms of fleet plans.Understand the implications of custom-built vs

standard vehicles.Understand the influence of the product on vehicle

selection.Be able to describe various handling aids and

options.

STUDY OBJECTIVES cont’

Discuss the options available with regard to driver comfort.

Understand the link between vehicle specification and performance.

Discuss the economics of vehicle replacement.Discuss the role of budgeting in vehicle selection.Be able to discuss leasing vs buying, particularly

in the context of ownership, operating, maintenance and other vehicle costs.

6.1 INTRODUCTION TO VEHICLE SELECTION AND DESIGN

6.1.1 THE IMPORTANCE OF VEHICLE SELECTION AND DESIGN

• Important that goods be loaded and unloaded and the vehicle turned around in minimum time.

• The product itself will determine the type of vehicle you need to acquire.

6.1.1 THE IMPORTANCE OF VEHICLE SELECTION AND DESIGN cont’

• When buying trucks for a new operation, it is essential to define the requirements as precisely as possible, for example

(i) where the vehicle will operate - in the city or in suburban areas;

(ii) on what terrain it will travel - flat or mountainous; and

(iii) what speeds the vehicle will attain.

6.1.2 CUSTOM-BUILT VERSUS STANDARD VEHICLE BODIES

• It is generally thought that a company which has a special vehicle body built for the carriage of their goods will pay a lot more than they would need to for a standard vehicle

• Increased cost incurred in building a special body can often be quickly recovered by economies and increased efficiency in operation.

6.1.3 THE VEHICLE AND THE PRODUCT

Once it has been decided that a custom-built vehicle is needed the following are the main points to be considered:

(a) Type of chassis – length, strength

(b) Size of body– load factor requirement for effective size

(c) Body design – flatbed, box (don’t make vehicle to specialised so

that it is not able to carry any other goods

6.1.3 THE VEHICLE AND THE PRODUCT cont’

(d) Choice of material– load to be carried– van carrying products stacked on the floor of the

vehicle only needs a body capable of acting as a cover

– if loads are suspended from the roof of the van, as in the case of the clothing industry and in meat haulage, then the body framing will be taking most of the weights

(e) Interior fitments– Loading aids like vehicle cranes and special

tracking for pallets makes loading unloading quick– walk-through cabs, – pallet loading, – demountable bodies, – power-operated tail loaders, – conveyors, – moving floors, built-In cranes, and interchangeable

containers.

6.1.3 THE VEHICLE AND THE PRODUCT cont’

6.1.4 HANDLING AIDS

• primary object of providing a handling aid with a vehicle is to load or unload that vehicle with the minimum effort and in the minimum time.

(a) Securing the loadThe interior of a vehicle can also be designed to

provide equipment, such as – Tie rails or – inflatable bags, to prevent the loads from moving.

6.1.4 HANDLING AIDS cont’

(b) Access to the load– For small parcel deliveries, a small door in the side

of a vehicle instead of only a rear door– Roller shutter– Roller shutter vs hinged rear doors depends on

type of operation

(c) Moving the load inside the vehicle– Pallet trucks, – wheeled cage pallets, – rollers, – overhead conveyor rails, and – the ‘Joloda’, • The ‘Joloda’ is a method of moving goods on normal

pallets or pallet boards by using special channels and rollers built into the floor of the vehicle which will enable these loads to be moved easily inside the vehicle.


(d) Moving the load onto and off the vehicle– Few problems arise in loading of a vehicle –

company premises– Problems arise at customers premises– fork-lift truck– Powered tail lift– vehicle crane,


6.1.5 DEMOUNTABLE BODIES AND CONTAINERS

• Flat vehicle or a box van• Solution - provide a demountable box (swop

body) container carried on a flat-bed truck. • Use of the demountable or ‘swop’ body

decrease the standing time of delivery• Increased vehicle utilisation produce a more

economical operation. • Swop body on Skeletal chassis or on a flat-bed

vehicle?

• The handling and movement of containers at ports and railway terminals is a specialised task, using equipment which is extremely expensive

• The container is essentially an extension of the demountable bodies principle.

6.1.5 DEMOUNTABLE BODIES AND CONTAINERS cont’

• Considerations when transporting a container with a truck:– Vehicle/trailer fitted with standard ISO container

fastenings [twistlock and container socket]– Bed on which the container is to fit must be

correct size.


Advantages of using a container:• Standard sizes exist so intermodal transport is

easier – adaptable to other forms of transport• Container can be removed and vehicle used as

normal flat truck• Containers last longer than a box vehicle• In the event of an accident, should the

container suffer damage, vehicle can still be used


6.1.6 ARTICULATED VEHICLES

• The Road Traffic act defines an articulated motor vehicle as “a combination of motor vehicles consisting of a truck-tractor and a semi-trailer.

6.1.6 ARTICULATED VEHICLES cont’

Articulated vehicles are very popular:greater payloads are possible “increased

volume” resulting in more economic operations. added flexibility which a tow-bar trailer

operation offers. (different trailers)

• Convertor dolly – axle on which a fifth wheel plate is mounted.


• The semi-trailer is connected in the normal way to this fifth wheel and the result is a tow-bar twin outfit.

• Advantage – trailer can be detached and moved to another destination, or even shunted around a factory or warehouse by a conventional tractor unit.


• The twin trailer (2 two axle semi-trailers)– conventional tractor coupled to a lead semi-trailer

which has been converted to tow a dolly. – The rear semi-trailer is connected to the dolly fifth

wheel to give a twin trailer towed by a single conventional tractor


6.1.7 DRIVER COMFORT

Ergonomics is the study of the human at work with or without machine, in an environment.

Applied to transport, this includes the comfort and safety of a driver in his cab, and the conditions to be met in handling his load onto and off the vehicle.

The driver must rely on the good sense and responsibility of the transport services management to provide comfortable conditions of work

6.1.7 DRIVER COMFORT cont’

• Driver comfort:– reclining seats, – adjustable headrests and armrests, – tinted glass, – carpets, – radio and tape players, – VHF equipment (radios), – air- conditioning and – sleeping facilitie

6.2 VEHICLE SPECIFICATION AND PERFORMANCE

6.2.2 OPERATIONAL FACTORS

(a) Configuration– achieve maximum payload,– maximising the ratio of payload-mass to vehicle tare

mass provides the best possible transport efficiency.– single vehicles or combinations ?• manoeuvrability,• carrying capacity, • number of drops (or load/unload time) and the • percentage of time that the full capacity of the vehicle

can be used in practice.

6.2.2 OPERATIONAL FACTORS cont’

(b) Body size and shape• The size and shape of vehicle bodies, semi-

trailers, tankers and trailers are usually determined by the characteristics of the commodities to be transported, e.g.:– Solid bulk– Liquid bulk– Hazardous materials– Temperature control etc.

(c) Speed• Increasing the speed (capability) of heavy

commercial vehicles could result in increased fuel consumption and additional capital outlay.


(d) Gradability and traction• The nature of the terrain over which the

vehicle is to be operated and the designed gross vehicle mass/gross combination mass (GVM/GCM) will determine the power output required


(e) Ancillary equipment• E.g: mounted cranes to off-load palletised loads,

rollers, overhead conveyor rails, tail lifts, gravity off-loading systems, etc.

• Should result in:– decrease in standing time at customers – more additional trip(s) of vehicle– increased productivity and better utilisation of capital

employed. – lower transport costs per unit transported.


6.2.3 TECHNICAL FACTORS

• (f) Additional equipment• Tyres – 2nd greatest variable expense• Fuel - greatest variable expense• Items that could reduce this expense:– Radial-ply tyres (reduces tyre flex)– Viscous clutch fans (disencages cooling fan)– Wind deflectors– Radio control systems– Tachographs (controlling driving techniques)

6.3 VEHICLE REPLACEMENT

6.3.1 INTRODUCTION• Vehicle replacement policy are defined in

terms of kilometres or years, or both.• An annual fleet review – identify the vehicles meeting these criteria and list

them in descending order of age or kilometreage. – Replacement of vehicles can be forecast at the

time of purchase, based on estimates of kilometreage and standard replacement age

6.3 VEHICLE REPLACEMENT cont’

• Vehicle replacement can be accelerated by the user and maintenance staff because of:– deteriorated vehicle condition, – accident damage, or – changes in the operating environment

• These conditions would warrant replacement evaluation before the replacement policy criteria for age and kilometreage are reached.

6.3.2 THE ECONOMICS OF VEHICLE REPLACEMENT

(a) Equipment life• A piece of equipment has a Service Life and a

Technological life• Service Life represents the amount of time

that the vehicle is capable of rendering service. – This life may be extremely long if the vehicle

receives adequate maintenance and if worn-out components are dutifully replaced.

6.3.2 THE ECONOMICS OF VEHICLE REPLACEMENT cont’

• Technological life represents the vehicle’s decline in productivity relative to newer models on the market – For example, a ten-year-old vehicle may be half as

productive as comparable current models.

Economic life - Period over which an asset (machine, property, computer system, etc) is expected to be usable.

• The economic life of a vehicle is the amount of time the total vehicle cost is at a minimum level.

• Tip: If total repair cost equals or exceeds 30% of the vehicle’s residual value, it should be considered for replacement.


(b) Life-cycle costing• The replacement of a vehicle is an annual

economic decision. • Aspects to consider when keeping or replacing

a vehicle:1. Company goals (growth, reduction of work, or

maintenance of the status quo).2. Old and new vehicles’ principal (initial

investment) and interest and depreciation.


• Aspects to consider when keeping or replacing vehicle cont’:3. Old and new vehicle maintenance costs. 4. Old vehicle resale value.5. Old and new vehicle operating costs.6. New vehicle manufacturer incentives.


• When these principal, interest, maintenance, and operating costs of the old vehicle are higher than the principal, interest, maintenance, and operating costs of the new vehicle, the old vehicle should be replaced.


6.3.3 THE BUDGETING PROCESS

• The budgeting process is the first step in replacement and provides the funds for the required vehicles.

• City vehicles show higher costs per kilometre and tend to be replaced at lower odometer totals.

• These are “harder kilometre s than highway or rural kilometres, which show increased costs only at higher accumulated kilometreages.

• The stop- and-go traffic patterns and congestion in the city are more expensive and cause greater wear than rural and highway travel.

6.4 LEASING VS BUYING

6.4.2 VEHICLE COSTSBasic concept of life-cycle costing• older vehicles should be replaced when the

cost of operating and maintaining them is higher than the price of a new vehicle.

• Optimum vehicle utilisation – lowest cost and greatest availability.

• Technical obsolescence also demands replacement.

6.4 LEASING VS BUYING cont’

• Ownership costs comprise the principal and interest costs incurred on a monthly basis until the vehicle is paid off.

• Operating costs include fuel, taxes, and registration fees.

• Maintenance costs include labour and parts– either scheduled or unscheduled. – Scheduled component costs are desirable since they

are lower than equivalent unscheduled component costs.

Total unit costs are affected by each of the following:

(a) Depreciation(b) Operations – rises gradually with fuel and tolls.(c) Maintenance(d) Downtime – vehicle not available for service(e) Obsolescence – obsolete - can’t do the job(f) Inventory costs – supports the repair function(g) Life costs – sum of fixed and variable costs


(c) Maintenance• Maintenance costs tend to increase as the vehicle ages. • Maintenance has the largest impact on replacement cost

benefits. • If this escalating cost is kept to a minimum by means of effective

scheduled maintenance – including preventive maintenance inspections, – effective driver control, and – timely component replacement,

• vehicles can be kept longer.

• THE END


Chapter 6 VEHICLE SELECTION. STUDY OBJECTIVES At the end of this chapter students will be expected...

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Transcript of Chapter 6 VEHICLE SELECTION. STUDY OBJECTIVES At the end of this chapter students will be expected...