Farm pickup trucks - your wants, needs and the compromises involved

Tuesday, March 8, 2016

Times have changed and with them the trucks that are needed for farm work. A check-list to help you make the right choices for your operation

by RALPH WINFIELD

As with almost all decisions on the farm, compromises are virtually inevitable, even when selecting a new or used pickup truck. Let us start with the want list:

• A reliable vehicle that is adaptable for many uses.
• A comfortable vehicle that is relatively easy to get in and out of.
• A second vehicle that can be used for family transportation when necessary.
• A vehicle that can be driven by a number of family members.
• A vehicle that serves as a truck but provides reasonable fuel economy.
• A vehicle capable of pulling a trailer (safely).

Then there are the needs:

• Does it require a double cab to carry workers to job sites or family members to social functions?
• How much payload can it carry if it is going to be used at planting time to carry seed or a fuel tank for the combines or tractors at distant farm sites?
• Will it be used to pull the seed/fertilizer wagon or the header wagon for the combine?
• Will it be used to pull heavy loads, such as a fertilizer spreader or loaded wagons at harvest time?

As you can see from this short list of wants and needs, there likely will have to be compromises made in selecting that one truck, or maybe it becomes clear that two pickup trucks or a combination of trucks might be necessary to meet all of those year-round and varied needs.

Truck lovers usually want strength, power and dependability. Let us start with strength first. This is usually determined by towing capacity. The towing capability rating is usually directly proportional to the weight of the truck and the power available. But don't forget that the transmission and final drives must be up to the task of providing the pull while keeping the engine torque at a high enough level to prevent power fade.

Power and torque. In an earlier article, I discussed the way in which engine torque and speed must be matched to maintain horsepower. If engine torque does not rise (increase) as engine speed is drawn down by a load, the engine can and will stall out.

This brings us to the transmission. It must provide sufficient down-shifting capability to prevent the engine speed from being reduced to a stall-out situation. Many of you, as truck drivers, know that you have to keep your revs up!

All engines used in tractors, combines and trucks must have good torque rise. In older gasoline engines, this was usually accomplished by having an "under-square engine." What that term means is that the piston (bore) diameter is less than the stroke length. This allowed the engine to produce a higher torque as engine loading pulled down the engine speed.

In newer engines with electronic injection control, a variety of system techniques, such as variable valve timing, are used to provide the necessary engine torque rise. But, again, the transmission combination or the shift down by the operator is still important. Many of us have become so dependent on automatic transmissions that we have forgotten how to double clutch as we shift down the transmission and/or the "DP" (double pinion) rear end.

(A stake truck I owned had a short-fourth transmission so, to avoid a miss-shift, I always had a reminder note attached to the dash!)

Towing capacity. The towing capacity ratings of full-sized pickup trucks have been rated by standard tests and range from 12,000 pounds up to 19,600 pounds. At the upper end, those trucks are producing up to 400 h.p. and up to 800 pounds per foot of torque.

The need for towing is usually dictated by the type of trailer required. They can vary from a small utility trailer to a relatively large livestock or travel trailer. All trailers pulled by trucks must be licensed and have the required lights.

Stopping capability. One of the greatest concerns is, and should be, the ability to stop those loads if and when necessary. Just over a year ago, I was rear-ended by a heavy pickup truck pulling a work trailer. I had braked to let a city bus out of a bus stop. The driver admitted fault and stated very clearly that if he had not had the trailer on behind, he would have been able to stop in time.

Virtually all pickup trucks operate with vacuum boost (powered) hydraulic braking systems, thus there is no pressurized air available as there is in larger trucks and tractor-trailer units.

In Ontario, all trailers with a Gross Trailer Weight (GTW) trailer plus load of 1,360 kilograms (3,000 pounds) must have brakes strong enough to stop and hold the trailer. A class G drivers license allows for a trailer GTW up to 4,600 kilograms (10,141 pounds). Higher GTWs are permitted for RV trailers only using a G license.

As a result, most trailers pulled by pickup trucks are fitted with separate electrical or hydraulic braking systems. If properly adjusted, they are very effective but can, as indicated earlier, create a short response delay which can cause rear-end collisions when operated in close proximity to other vehicles.

Basically, there are two types of electric braking systems. The most common is the surge system that is activated only by a resistive load on the hitch. It is simple and effective, but it can create a minor problem when you attempt to back a trailer up hill. The second, more sophisticated system has a dash-mounted control that can be operated manually to override or limit a heavy trailer push.

The other system is hydraulically based but not connected directly to the truck's hydraulic brake system. It uses a surge activator. This system was used extensively for boat trailers before newer electrical system were built to be more water-tolerant.

Braking loaded grain wagons. Many of us who pulled wagons behind tractors to take grain or oilseeds to the local elevator learned very early on not to follow any vehicle too closely. We depended on the tractor brakes to stop those wagons. Many of us well remember those skids, especially on loose gravel or wet pavement.

Almost all large hopper wagons in use today have, or should have, hydraulic braking systems operated from the tractor cab. This is especially critical if multi-wagons are being pulled simultaneously or if there are steep downhill road slopes on the way to the grain elevator or storage facilities.

To put this loading in perspective, two 500-bushel wagon loads of soybeans would have a product weight of 27,216 kilograms (60,000 pounds). Add the weight of the wagons and you can appreciate the need for an effective braking system.

Most of the wagons that I have seen only have a large-diameter, hydraulically-operated disk brake on each rear wheel. This braking system can be activated manually using pressurized hydraulic fluid from the tractor or connected directly into the hydraulic braking system common on the bigger tractors necessary to pull those larger wagons safely. It should be evident that a surge braking system at the hitch point would be entirely unsuitable for this application with multiple wagons going downhill.

Fuel efficiency. We all want to travel economically. Unfortunately, large heavy pickup trucks do not allow this to happen. It takes energy in the form of fuel to start and operate a relatively heavy pickup truck. These pickup trucks also have a large front face that creates a relatively high air (head-wind) resistance.

Diesel engines are generally more fuel-efficient than their gasoline counterparts because of the higher compression/expansion ratio. That means that the exhaust gases are expanded more and therefore give up more heat as useable power.

Other larger gasoline engines have been designed to deactivate cylinders or stop and start to improve fuel efficiency. Some new pickups are being built using lighter weight materials, such as aluminum, to reduce mass and therefore the energy required to start and stop them.

Pickup truck usage and expectations have increased dramatically in the last 15 years and will continue to evolve as they are used for higher-level tasks, such as pulling those big combine header wagons between farms and fields or those large equipment or livestock trailers.

Many of us thought we had a big combine when we reached the 15-foot header range. By 2015, most new combines are arriving with 30- to 40-foot headers. The productivity and the need to move grains and oilseeds from the field have also changed dramatically.

How many of you remember when we moved grain from the field with 100- to 150- bushel hopper wagons? We seldom used our older lightweight pickup trucks to take that grain to the elevator. Nor did we have to pull the combine header or the larger loaded fertilizer spreaders. Times have changed and pickup trucks have changed with the needs and wants. BF

Agricultural engineer Ralph Winfield farms at Belmont in Elgin County.