1. One way plow ref: www.tradevv.com
t
Two-way plow ref: http://sdycdadi.en.made-in-china.com/productimage/PStEJdjDaxWi-2f0j00QZjECNasYfoT/China-Reversible-Plough-Roll-Over-Plow-Hydraulic-
Reversible-Plow.html

2. Switch plow ref:F armequipmentusa.com
Primary Tillage implements;wooden plough or Indigenous plough,Soil Turning Ploughs,Mouldboard Plough,Disc Plough,Turn-wrest or Reversible or One-way
Plough,Subsoil Plough,Chisel Plough:,Ridge Plough:,Rotary Plough or Rotary Hoes:,secondary Tillage Implements,Tractor Drawn Cultivator:,Sweep Cultivator
Harrows,Disc Harrow,Blade Harrow,indigenous Blade Harrows,Plank and Roller
All about tillage
Tillage is the agricultural preparation of the soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered
tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking. Examples of draft-animal-powered or mechanized work include
ploughing (overturning with moldboards or chiseling with chisel shanks), rototilling, rolling with cultipackers or other rollers, harrowing, and cultivating with cultivator
shanks (teeth). Small-scale gardening and farming, for household food production or small business production, tends to use the smaller-scale methods above,
whereas medium- to large-scale farming tends to use the larger-scale methods. There is a fluid continuum, however. Any type of gardening or farming, but especially
larger-scale commercial types, may also use low-till or no-till methods as well.
Tillage is often classified into two types, primary and secondary. There is no strict boundary between them so much as a loose distinction between tillage that is
deeper and more thorough (primary) and tillage that is shallower and sometimes more selective of location (secondary). Primary tillage such as ploughing tends to
produce a rough surface finish, whereas secondary tillage tends to produce a smoother surface finish, such as that required to make a good seedbed for many crops.
Harrowing and rototilling often combine primary and secondary tillage into one operation.
"Tillage" can also mean the land that is tilled. The word "cultivation" has several senses that overlap substantially with those of "tillage". In a general context, both
can refer to agriculture generally. Within agriculture, both can refer to any of the kinds of soil agitation described above. Additionally, "cultivation" or "cultivating"
may refer to an even narrower sense of shallow, selective secondary tillage of row crop fields that kills weeds while sparing the crop plants.
Tillage has been an important aspect of technological development in the evolution of agriculture, in particular in food production. The objectives of tilling the soil
include seedbed preparation, water and soil conservation and weed control. Tillage has various physical, chemical and biological effects on the soil both beneficial
and degrading, depending on the appropriateness or otherwise of the methods used. The physical effects such as aggregate-stability, infiltration rate, soil and water
conservation, in particular, have direct influence on soil productivity and sustainability.
Tillage technology began with the use of stick or metal jab for seeding and with gradual agricultural development the technology passed through a phase of ploughing
- animal-drawn ploughs, subsequently followed by tractor-drawn implements and recently with more powerful machinery. At the centre of all this development, is
the availability and employment of energy sources. In developed countries and in some developing countries today, fossil fuel is the main energy source, whilst in
most developing tropical countries human labour is still predominant. However, animal draught power has been the tradition in many developing countries,
particularly in the semi-arid tropics. A major constraint on the use of animals is and has been the availability of adequate fodder.
Ref: http://www.fao.org/docrep/t1696e/t1696e08.htm
Tillage has been and will always be integral to crop production. Tillage can result in the degradation of soil, water, and air quality. Of all farm management practices,
tillage may have the greatest impact on the environment. A wide variety of tillage equipment, practices and systems are available to farmers, providing opportunities
to enhance environmental performance. These opportunities have made tillage a popular focus of environmental policies and programs such as environmental
indicators for agriculture.
Ref: http://www.sciencedirect.com/science/article/pii/S0301479706002532
Factors to consider in planning a crop production building

3. Legislation
Planning Permission
Many smaller farm buildings may not need planning permission. Full details of the circumstances under which buildings may be exempt are given in the Town and
Country Planning General Development Order 1977, Appendix 5. But as the regulations are not always easy to interpret you will probably find it helpful to ask the
Borough Council’s planning officers for advice. Even if planning permission is unnecessary, the advice in this guide is worth considering. A building constructed in
accordance with the advice is likely to be a credit to a farm and its surrounding area. Only a relatively small proportion of farm buildings actually require planning
permission. The majority of these require permission either because they are close to a road (and so are prominently visible) or because they are large enough to
have a major impact on the countryside, whether or not they are prominently sited. So it will normally be a requirement of the Council that farm buildings are
coloured and details of colours to be used should be submitted with the planning application.
Building Regulations
Exemption from planning control does not mean exemption from Building Regulation Control. The two are quite separate, and the Council’s Building Control officers
should always be contacted even on buildings that do not need planning permission to discuss what permission may be needed.
Listed Buildings
Some farmhouses and other farm buildings in the District are ‘listed’ by the Department of the Environment as being of special architectural or historical interest. No
change which affects their character or setting should be made until ‘Listed Building Consent’ has been given by the Borough Council. External or internal changes or
a new building close by, may all need consent, so it is important to check with the Council’s planning staff before making any firm decisions.
Siting
The siting of a new farm building, its arrangement on the site and its relationship with any adjoining buildings all have a direct bearing both on its efficiency and
profitability and its appearance in the landscape. The objective should not be to hide or to camouflage the building but to fit it into the lie of the land. A well sited
farm building should appear to be just as much a part of the landscape as woods, hedgerows and country lanes, most of which are equally man-made.
Siting is probably the most important single factor affecting the building’s usefulness and appearance. Decisions on siting should not be arrived at hastily. There is
usually more than one possible site for a new building and there are a number of points to be taken into account when deciding upon the best one.
Access
It is important to consider the proposed site in terms of its effectiveness and convenience in relation to the farm as a whole. This includes the movement of
machinery, materials and stock from the surrounding road system and to and from the fields and other buildings on the farm. The cost of widening or resurfacing
unsuitable tracks and the cost of new roads should
be taken into account as well as the effect these additional works will have upon the appearance of the building when completed
Services
The availability and cost of’ providing services such as electricity and water will need to be considered at an early stage. Where mains supplies are not available
alternatives will need to be investigated, for example, streams in the case of water and independent generators in the case of electricity. Where there is a choice of
supply costs can be compared.
Views
In the first instance it is necessary to determine the obvious view points from which the proposed building would normally be seen, for example, from roads,
footpaths, nearby villages and towns, picnic sites, car parks, etc. This may mean viewing the site from several miles away especially in upland areas. From the various
vantage points the impact of a proposed building can be assessed and alternative sites compared. By assessing a proposed site in this way it is often possible to
discover relatively minor changes to siting and layout which can result in considerable improvements to the overall appearance of the building in the landscape
Skyline Sites
A building on a skyline will tend to dominate the landscape; breaking the horizon between land and sky. In flat open landscapes a well designed building seen against
the sky can make a positive contribution to the landscape. However in most other circumstances such development breaks an accepted natural line between sky and
land. Re-siting, where possible below the skyline considerably reduces the intrusion of hard straight lines into the landscapes. Where this is not possible careful
attention should be given to the size, outline and colour of the building and its relationship with the contours of the land. The outlines of the building should be
interesting and well balanced. (The distant views of buildings in this situation are particularly crucial.)
Topography
The relationship of a building to the contours of the land is fundamental to its overall appearance. Traditional farm buildings often seem to grow out of the land,
partly because they were built of traditional local building materials but partly because the builders shaped each building to fit the site. With larger new buildings this
is not quite so easy to achieve. However through careful siting the lines of a building can be softened by the presence of a landscape backcloth and by careful design a
building can hug the sweep of the land closely.
A sloping site, although it may seem more difficult to develop, should not be ignored as it may have several advantages:
1. Setting a building into a slope will minimise its impact on the landscape and will help it to merge into its surroundings.
2. The slope can give shelter and a warm aspect.
3. A sloping site may well be less productive agricultural land.
4. The spoil from excavation can often be used to reduce the apparent height of the building through ground shaping.
Cut and fill is the best method of providing a level building site on a steep slope and of setting a building into the landscape. For both economy and appearance,
however, it is best to keep the cut and fill to a minimum. This can be done by either terracing along the contours of a slope rather than across them. Siting a building
on a steep slope without cut and fill and particularly siting a long building at right angles to the
contours on a steep slope so that it seems to jut out of the hill and end on a high retaining wall should both be avoided from the point of view of appearance, cost
and stability.
Grouping and Scale
From a distance the detail of a building becomes less apparent. What counts is the relationship of one building to another - their grouping and scale. Wherever
possible new buildings should form part of a group rather than stand in isolation and should have a relationship of size, style and finish to the rest of the group.
Existing Buildings
As already mentioned, traditional farm buildings have played a big part in forming the character of the countryside and they may be of interest in their own right. It is
hoped that farmers will make efforts to keep these buildings and adapt them to modern use wherever practical. In villages, particularly Conservation Areas* or places
of special character it becomes all the more important to retain traditional farm buildings. The loss of a large building or group always diminishes the character of a
village and the Council will give sympathetic consideration to new uses for such buildings where they are clearly impractical for modern agriculture.
The addition of a new farm building to a group of existing buildings has advantages and disadvantages. It can be an excellent way of fitting a new farm building into
the landscape and at the same time enhancing the appearance of the group as a whole. However in order to be successful a number of points need careful
consideration. The addition of a new farm building to a group of existing buildings has advantages and disadvantages. It can be an excellent way of fitting a new farm
building into the landscape and at the same time enhancing the appearance of the group as a whole. However in order to be successful a number of points need
careful consideration.
1. The contribution made by the new building to the existing group in terms of providing shelter and enclosure to circulation spaces, yards and other buildings.
2. The compatibility of new and old in terms of sizes, style, colour and materials.
3. The opportunities for further expansion of the building in future without affecting others.

4. 4. The possibility of moving existing buildings which serve little purpose and are of no visual or architectural interest.
*Consent is needed to demolish any building in a Conservation Area.
Awkward siting requires extensive cut and fill and results in ugly retaining walls and bare slopes
Taking advantage
Existing Trees
Trees should be retained as far as possible. They are an invaluable asset in softening the structural outlines of new buildings and settling buildings into their
surrounding landscape. Their removal may well expose an unattractive building to a critical viewpoint. New planting is discussed in a later section of this guide.
Form & Scale
Due to their increased size, modern farm buildings may be out of scale with neighbouring traditional farm buildings and with the accepted scale of the surrounding
landscape. This effect can be reinforced or muted through the choice of site, the colour of the building and its form. The apparent size of a building and its impact on
the landscape is particularly influenced by its form. A single large rectangular building will have the greatest impact. Two smaller buildings instead may not only
appear less intrusive but could be more flexible in use. A variation in roof height can also reduce the scale of a building and can save the cost of additional structure
and cladding and avoid having an unused space that simply absorbs heat and light. The breaking up of large unrelieved gables can sometimes be achieved at little or
no extra cost. It also helps to reduce the scale and visual impact of a large building.
Cladding Materials
Walling Materials
External Works
The appearance and efficiency of a well designed building can be spoilt as a result of thoughtless additions and lack of attention to external works, such as fuel tanks,
silage clamps, slurry tanks, fences, gates, access roads and services. This can usually be avoided if the external works are considered at an early stage in the design of
the building. Improvements can also be made through a consistent approach to the use of colour and materials, which helps to unify the finished site and present a
tidy appearance.
Fences, Walls and Hedges
After the completion of a new building adjacent fences, walls and hedges should be restored. This will help to link the building into the landscape, create enclosure
and provide privacy and shelter. The materials and methods of construction used should reflect local styles and practice wherever possible.
Site Restoration
Some farm building sites look unfinished long after the building itself has been completed due to the indiscriminate dumping of evacuated material and failure to
replace topsoil. Often topsoil and subsoil are mixed which leads to unsightly wet areas where little can grow. This not only spoils the appearance of a building but is a
waste of good land. Topsoil should be carefully stripped and stored separately from subsoil, and on completion of the building, the surrounding area not required for
hardstanding should be soiled and grassed over or cultivated.
Trees
References: http://www.harrogate.gov.uk/Documents/DS-P-FarmBuildingsDesignGuide1986.pdf
Future expansion
Battery control-Battery contr module is a control unit to control battery load functions
Battery charging controller-A controller for a solar electric generator that permits the generator to produce power substantially at its maximum capacity while also
providing efficient charging at three charging stages; i.e., bulk charging, acceptance charging and float charging. Power is transferred from the generator to a
temporary electric storage device that is periodically partially drained of power to maintain the temporary electric storage device at a voltage corresponding to the
voltage needed by the generator to provide maximum generator power. The electric power drained from the temporary storage device is used to charge
conventional batteries. In a preferred embodiment, the temporary storage device is a capacitor that is part of a buck regulator operating at 50 kHz with duty factor
control between 0% and 100%. This buck topology switching type regulator provides the periodic draining. In the preferred embodiment control of the duty factor of
the buck regulator is utilized to limit current, to prevent battery over charging, to test for the voltage corresponding to maximum power, and to operate the solar
generator at is maximum power voltage. When operated at its maximum power operating point, the output to the battery is constant power, providing greater
battery charge current than prior art controllers. Additional controls are provided to adjust battery charge voltage to permit maximum current flow during bulk
charging, and at a first pre-selected charge voltage during acceptance charging and at a second pre-selected charge voltage during float charge. In a preferred
embodiment provision is made for periodic equalization overcharging to improve battery performance and lifetime.
Conventional & Non-Conventional Sources of Energy
By Mark Kennan, eHow Contributor
1. Types
o Conventional sources of energy usually include fossil fuels like coal, natural gas and oil as well as nuclear power. Nonconventional sources include solar power,
hydropower and wind power.
Benefits
o Fossil fuels are inexpensive and require established technologies that can produce energy around the clock. Nonconventional energy sources have a much smaller
environmental footprint and are renewable.
o
Disadvantages
o Conventional sources of energy have a limited supply because eventually the nuclear elements and fossil fuels will be used up. In addition, burning fossil fuels release
significant amounts of greenhouse gases and contribute to acid rain. Nonconventional energy sources are still expensive and are often limited to producing energy
only under certain circumstances such as sunny days for solar plans and windy days for windmills.
Size
o Fossil fuels provide about 85 percent of the energy in the United States, and oil provides almost all of the energy for automobiles.
Potential
o Even though there are significant environmental costs associated with fossil fuels, the U.S. Department of Energy expects their usage to increase of the next 20 years
because nonconventional energy sources will not develop quickly enough to meet the growing energy demands.
Conventional Energy Resources
Conventional energy resources, or the fossil fuels oil, gas and coal, provide more than 85 percent of energy consumed in the United States. Conventional resources
provide two-thirds of the country's electricity and almost all transportation fuels. Though conventionally sourced energy may have a lower initial cost than non-
traditional energy sources such as solar or geothermal, the U.S.'s reliance on fossil fuels presents many challenges, including environmental damage, reliance on
military presence to secure resources and lack of sustainability.
1. Oil
o The U.S. Department of Energy describes oil as "the lifeblood of America's economy." More than 40 percent of total energy used in the U.S. comes from oil, or about
18.8 million barrels per day. Of the fuels used for transportation, such as in cars and trucks, 99 percent comes from oil. According to the U.S. Department of Energy,
the country faces two constant and immediate oil-related concerns: "an immediate readiness to respond to oil supply disruptions and keeping America's oil fields
producing in the future." These concerns can be best understood when viewed in a global context.

5. As of 2009, the U.S. imported 63 percent of oil, or 11.7 million barrels per day, from foreign countries. The top five import sources are Canada, Mexico, Venezuela,
Saudi Arabia and Nigeria. The U.S. Energy Information Administration states that, at current consumption levels, the global supply of oil will be adequate for another
25 years, a figure that is surrounded by "substantial uncertainty about the levels of future oil supply and demand." The U.S's heavy reliance on oil also poses
environmental issues. Oil production and consumption are responsible for about 42 percent of the country's carbon dioxide greenhouse gas emissions.
2. Natural Gas
o According to the U.S. Department of Energy, 900 of the next 1,000 power plants constructed will use natural gas, reflecting an increase in the fuel's popularity. In
2008, the U.S. consumed 23 trillion cubic feet of natural gas. Natural gas resources provide about 30 percent of electrical power overall, including 29 percent of
energy used in industrial applications and 21 percent of the residential energy supply. The U.S. Energy Information Administration estimates that more than 550
trillion cubic feet of dry and wet natural gas reserves lie within U.S. borders. Natural gas production and consumption is responsible for about 22 percent of carbon
dioxide greenhouse gas emissions.
o
Coal
o The U.S. Department of Energy describes coal as "one of the true measures of the energy strength of the United States," as one quarter of the world's coal resources
are thought to be inside U.S. borders. More than half of the nation's electricity comes from 5,400 coal-powered plants, and the world's coal resources are believed to
contain more energy potential than the world's oil resources. In 2009, the U.S. exported more than 26.2 million short tons of coal and imported 22.6 million tons. The
U.S. Energy Information Administration estimates that 17,468 million short tons of recoverable coal reserves exist in the U.S. Top coal producing states include
Wyoming, West Virginia and Kentucky. Coal production and consumption create 36 percent of the U.S.'s carbon dioxide greenhouse gas emissions.
The Definition of Conventional Sources of Energy
Your Dictionary.com defines conventional as "not unusual or extreme; ordinary." This fits well with conventional energy sources in terms of being not unusual;
however, the impact on society by these sources has been anything but ordinary and has actually been quite extreme. Conventional energy sources have
demonstrated both positive and negative consequences. The negative effects have fueled the proliferation of alternative energy sources in recent years
1. Features
o Traditional energy sources consist primarily of coal, natural gas and oil. They form from decaying plant and animal material over hundreds of thousands to millions of
years. Most of these sources are burned to produce energy through power plants and automobiles.
Effects
o Being carbon-based, natural gas, oil and coal store carbon as potential energy and release it when burned. The Intergovernmental Panel on Climate Change states
that carbon and other greenhouse gas emissions are a major culprit in climate change.
o
Disadvantages
o According to the Energy Information Administration, burning coal produces sulfur, nitrogen oxide and mercury emissions. All of these are known to have disastrous
environmental and health consequences.
Significance
o Conventional energy sources made the Industrial Revolution possible. This movement started with England's textile industry in the 18th century and made much of
what is considered "modern society" possible.
Features
o Carbon-based energy sources are nonrenewable, meaning they will run out at some point. Most alternative energy sources (wind, geothermal) will theoretically
never run out.
http://www.ehow.com/facts_5019797_definition-conventional-sources-energy.html
http://www.ehow.com/facts_5522988_conventional-nonconventional-sources-energy.html
Research Topics on the Global Implementation of Non-Conventional Sources of Energy
The term conventional energy typically refers to power generated by fossil fuel sources, which are associated with many health, environmental and political
problems. By contrast, non-conventional energy is derived from natural resources, such as wind, sun and hydro-electric power. With concerns worldwide over the
negative effects of conventional energy, governments and private firms have begun to direct attention and investment toward non-conventional sources. The global
implementation of non-conventional alternatives is a rich research topic consisting of several components.
1. Global Demand
o One area of research on the implementation of non-conventional energy is the global demand for alternatives. Research topics include an examination of the
environmental factors driving global need, such as concern over the greenhouse gas emissions and global warming associated with conventional fossil fuel-based
sources. In their 2007 assessment report, the Intergovernmental Panel on Climate Change, the world's leading scientific and political authority on global warming,
maintains that man-made greenhouse gas emissions are the primary cause of global warming. Research topics on global demand also include the health risks to
human and animal life associated with conventional sources, and how the use of non-conventional sources minimizes hazard.
Energy Types
o There are multiple sources of non-conventional energy, most all of which are derived from renewable natural resources, such as sun, wind, hydro-electric power and
agricultural biomass. Research on the global implementation of these sources includes examinations of the different varieties currently available, the varieties being
tested for future development and implementation, and the history of research and development in this field. Research topics also include the regional variations in
non-conventional sources, such as hydro-electric dams in Brazil's Iguazu Falls, wind farms in the American Midwest or the Chinese Seven Gorges project.
o
Source Comparisons
o While non-conventional energy sources offer many benefits in comparison to conventional sources, they have different levels of efficiency and cost. One important
topic of research is the examination of the different energy output levels afforded by different sources. The discussion of efficiency is closely tied to available funding,
regional resource availability and energy storage issues.
Barriers to Implementation
o Although governmental and scientific bodies are increasingly aware of the global need to move away from dependence on conventional energy sources, the
worldwide implementation of non-conventional sources remains hampered by several barriers. An important topic of research is the examination of existing barriers
to implementation. Such barriers include conflict of interest by existing fossil fuel corporations, lack of international consensus, geopolitical resource disputes and
limitations in available funding. Another important dimension to the challenges in implementation is the social impact of generating non-conventional energy. While
large-scale alternative energy infrastructure can provide valuable services to the public and private sector, these structures can also displace communities or
indigenous groups from their areas of settlement, as noted by the World Health Organization.
http://www.ehow.com/info_8240916_research-implementation-nonconventional-sources-energy.html
The Importance of Non-Conventional Sources of Energy

6. As the world's finite supplies of traditional fossil fuels are consumed at a voracious rate by a continually industrializing world, the development and use of non-
conventional sources of energy is becoming ever more important for the future of the planet. Some research has shown that fuels such as oil and gas, and even
nuclear, have a remaining lifespan of as little as 70 years.
1. Green Energy
o There is considerable debate about the efficiency of "green", or non-conventional, energy and its ability to supply the world, particularly the
developed countries, with enough electricity or fuel for their ever increasing needs. Despite campaigns to encourage people to the principle of the
"three Rs" -- reduce, reuse and recycle -- to minimize the consumption of energy and natural resources, the rate at which fossil fuels are
consumed continues to rise and, consequently, damage the environment.
Renewable Solutions
o The contribution of renewable sources of energy to demand and consumption remains small, at around just eight per cent of the total in the
United States, for example. However, it is a growing sector and expanding levels of investment in some countries has seen renewables forming a
larger share of the supply in those nations. Wind turbines, wave and tidal generators, solar capture, geothermal harnessing and hydroelectric
projects are all capable of providing a limitless supply of clean energy.
o
Clean and Green
o All over the developed world, the importance of non-conventional energy has been recognized, with international targets for a massive increase in
renewable generation output being set. However, almost everywhere these ambitious targets have been missed. For instance, the United Kingdom
generates just 6.5 percent of its energy from green or renewable sources so will need a massive increase to achieve the 30 percent of output
demanded by the European Union by 2020.
Fuel Types
o But it is not only in electricity generation that non-conventional energy sources are growing in importance. If we want to continue to drive
automobiles, many experts believe we will all need to embrace electric cars or biofuels to power those with more traditional engines. Biofuels are
derived from a number of areas, including such as ethanol or diesel from plant materials, methane from animal waste, and liquids made from
wood and bark chippings, and straw.
http://www.ehow.com/info_8329761_importance-nonconventional-sources-energy.html
automatic draft control-A flue damper control includes a flue pipe, a damper in the flue pipe and an electro-mechanical control for opening and closing the damper
according to thermostatically controlled conditions. The damper control is provided with an adjustment means to adjust the "full" open and "full" closed positions of
the damper vane.
1. A furnace flue gases control device for regulating the damper vane in a flue pipe comprising;
a flue pipe section having a damper vane therein;
a shaft for rotating said damper vane, said shaft extending at least through one side of said flue pipe section;
a pinion gear affixed to the shaft end extending through said side of said flue pipe section;
a toothed rack engaging said pinion for rotating said damper vane to an open position;
a solenoid for reciprocating said toothed gear rack;
a return spring for returning said damper vane to a closed position;
a switch means for controlling a furnace burner circuit; and
a lever on said pinion gear for switching said switch means, wherein said solenoid and said switch are adjustable to change the open and closed positions of said damper
vane.
www.freepatentsonline.com/4138060.html - Cached
about theoretical time
Time appears to be related to change which is apparent to us through presence of motion and forces at macro as well as micro level. Present is like a sharp point of a
recording needle and it gives us the most real feel of time. Present does not have a measurable duration although we can measure the passage of time. Past and
future are durations that can be measured although they cannot be accessed. This suggests that our perception of time as past present and future may just be an
illusion created by our mind as it tries to make sense of changing world around us. Similarity in the time characteristic of past present and future in fictional
stories as well as real historic events again points toward past being just a memory.
http://www.timephysics.com/
automatic control position control-An automatic position control apparatus for a ground working vehicle equipped with a liftable working implement. The control
apparatus is adapted to automatically control lifting and lowering of the implement so that the deviation of the draft value of the implement acutally detected by a
draft detector from the draft value preset by a draft setting unit is maintained within a permissible range preset by a sensitivity setting unit. The control apparatus is
characterized in that the apparatus includes a detector for detecting that the deviation is not decreasing outside the permissible range above the maximum
permissible value thereof so as to automatically control the lift of the implement only while the deviation detector is in detecting operation.
http://www.google.fr/patents/US4300638