How to Use a 4 Wheel Hay Rake
b y GJ Stoltz (Reg Eng Tech)
Hay had to be raked with crude hand tools until the early 1800's, when the horse-drawn sulky rake was developed.
Rakes were developed to gather newly-cut hay into small piles, or windrows, to make hay collection easier. Rakes lift mowed hay from the swath and place it in a loose, fluffy windrow with the green leaves inside, protected from the sun's rays. The leaves retain their fresh, green colour, while the stems cure. Rakes are also used to windrow straw and crop residue for harvest or burning. Rakes are sometimes used to turn windrows for even exposure to the sun.
A swath is the strip of cut material left behind a mower, and a windrow is the strip of material left behind a rake.
Tedding indicates the spreading of the swaths left by the mower, or windrows.
These swaths, or windrows, are uniformly spread over a wide area in a fluffed-up state, exposing the material previously covered to the sun and wind to improve the drying rate.
We thank the ARC-Agricultural Engineering in South Africa for making their manual on rakes and tedders available to the readers of ProAgri Zambia.
Types of rakes
Two types of rakes that are very popular on the Southern African market will be discussed in this article series, namely the self-rotating finger wheel and the rotor rake.
Self-rotating finger-wheel rake (see Figure 1): The rake is mounted on the three-point-hitch of a tractor. The finger-wheels have teeth radiating from a centre hub.
These long teeth flex along their entire length and float around obstructions that could break short, stiff teeth (see Figure 2). However, in windy conditions some finger wheels are susceptible to crop tangling and wrapping on the wheels, which results in poorly formed windrows. Severity of the problem is usually related to the diameter of the centre hub where the teeth are attached. Windshields are available for some finger-wheel rakes.
Figure 4: With spreading, the hay is passed between the finger-wheels.
When set for raking, the finger-wheel rakes move the hay along from one finger-wheel to the next (see Figure 3). Some models can be set to pass the hay between the individual finger-wheels, and by doing so the hay is spread and the windrows are demolished (see Figure 4).
With the big, round baler, and its wider windrow requirements, a finger-wheel rake can be extended by mounting two four-wheel finger-wheel rakes onto one frame in a V-formation. With this machine, the hay is raked from both sides to create a windrow at the centre of the rake (see Figures 5 and 6). The finger-wheels, with readily attached spring steel fingers, are set at an oblique angle to the direction of travel and are caused to rotate by ground contact as the tines are pulled over the ground.
The four-finger-wheeled rake is very popular because of its relatively low price, simplicity of design and variety of functions.
As this rake relies on tine-to-ground contact to induce finger-wheel rotation, some contamination of the hay by soil and stones occurs. This can be aggravated by incorrect setting and control of the operating height which may exert too much pressure on the finger-wheel tines.
Although the finger-wheel rake is gentle in handling crops such as lucerne, it has a tendency to roll the hay and in crops such as eragrostis, roping may occur.
Working speed
The land speed is normally determined by surface conditions and also by the type of crop being raked. In brittle crops where leaf loss may occur, it may be necessary to work at a reduced speed. When raking lucerne, for instance, the land speed may vary between 6 and 8 km/h.
Direction of raking:
The finger-wheel rake moves the hay from right to left but it is immaterial to which side the hay is raked. Where raking losses are high, it is recommended that the rake is operated in the same direction as that followed by the mower, as this may improve the raking action (see Figure 7).
Working widths:
The working width of all finger-wheel rakes can be altered by changing the angle of the main frame to the direction of travel. Altering this angle also influences the distance the hay is moved from the swath. Some finger-wheel rakes can also be fitted with additional finger-wheels to increase the working width. The raking width of a rake with four finger-wheels will approximately be 2,5 metres and 5,4 metres for an eight-wheel rake. At a land speed of 8 km/h and a working width of 2,3 metres, a rake can do 1,6 hectares per hour.
Planning and preparation:
Planning for raking means to be ready when the hay is ready. Since a rake does not require much power, it is often used with an old tractor. This is acceptable, but be sure that the tractor is reliable because an hour lost due to a breakdown can cause hay to dry too much for raking.
Hook-up preparations:
(Since specific procedures vary with each make and model, consult the
operator's manual for details).
- An 18-kW tractor can be used on a four-wheel rake and a 35-kW tractor on an eight-wheel rake.
- Move the tractor's drawbar so that it will not interfere with the rake (see Figure 8).
- Check and adjust the three-point linkage on the tractor for correct operation (see Figure 9).
- Adjust the wheel spacing on the tractor if necessary.
- Add a nose weight to the tractor if it seems that the rake is very heavy and the tractor needs more stability.
- Adjust the hitch-pin locations on the rake's main frame to match the tractor's three-point hitch.
- Back the tractor into position and lower the draft links until they are approximately in line with the hitch pins.
- Connect the draft links to the hitch pins.
- Attach the tractor's top link to the rake's upper hitch point (see Figures 10, 11, 12, 13, 14, 15 and 16).
- Level the rake from side to side, using the draft links.
- Adjust the tractor's hitch sway blocks or stabilisers so that the rake won't swing from side to side.
- Raise and lower the rake with the three-point hitch to check for interference between the rake and tractor wheels as well as the tractor's drawbar.
- Readjust the hitch position if necessary.
- Lubricate the rake as recommended in the operator's manual.
- Tighten bolts and nuts to the
recommended torques. - Replace damaged teeth.
- Turn the finger-wheels to make sure they are turning freely.
- When in the field, the float spring must be adjusted to avoid too much weight on the finger-wheels (see Figure 17).
Troubleshooting:
Problem
- The rake is missing, or skipping hay.
Probable causes
- Some of the finger wheels have broken teeth.
- The rake is bouncing too much.
- The tractor is travelling too fast.
Problem
- Excessive tooth breakage.
Probable causes
- The tractor was driven backwards with the teeth touching the ground.
- Too much weight is carried on the finger-wheels and the float spring must be adjusted.
- The fields are too rocky or the terrain is too rough for the rake.
Problem
- Hay is clogging on the finger-wheels.
Probable causes
- The field is too wet to rake and mud is clogging on the fingers of the finger-wheels.
- The hay is caught in the coils of the fingers on the finger-wheels because the float spring must be adjusted to put less tension on the finger-wheels.
Next month we shall look at the single-rotor rake. Published with acknowledgement to the ARC-Agricultural Engineering for the use of their rakes and tedders manual. Visit www.arc.agric.za for more information.
Source: https://www.proagri.co.za/en/the-operation-and-application-of-hay-rakes-and-hay-tedders/