Ridges on the pad are one of those problems that look like a driving error until you start ruling things out. The operator slows down, opens the door a fraction less, tries a different line across the pen. The ridges come back. On a single-auger machine in the 1006 class, three mechanics are almost always in play before anything else gets blamed.
How Door Opening and Ground Speed Interact on a Small Single-Auger Unit
On a high-volume dual-auger spreader, the auger flight volume is large enough that small changes in ground speed smooth themselves out across the swath. On a compact single-auger machine, that margin is much thinner. The auger delivers a narrower, more concentrated stream to the expeller, and the expeller throws what it gets. If the door is open wider than the forward speed can compensate for, you get heavy deposits in the centre of each pass. If it is barely cracked and the tractor is moving slowly, you get the same effect: too much material stacking in one spot before it clears.
The four variables are door opening, expeller rpm, deflector shield position, and tractor speed. Change one without adjusting the others and the pattern will tell you immediately. On the 20 Series side discharge machines, door opening controls the volume of material discharged, expeller rpm controls particle size and arch height, the deflector shield controls spread width, and ground speed controls application rate density. All four interact. On a smaller 1006-class unit, the tolerances between those variables are tighter than most operators expect, because the auger and expeller are physically smaller and the buffer between a correct setting and an overloaded one is narrower.
Late winter material in the Free State tends to be pen-packed and dense. It does not flow onto the expeller the way lighter, moisture-rich manure does in spring. That density amplifies every door-speed mismatch. What would have been a barely noticeable stripe in wetter conditions becomes a proper ridge in hard, compacted material.
Worn Flighting Tips Produce Pulses, Not Flow
This is the one most operators miss. When the tips of the auger flighting are worn, the flight no longer pushes material consistently toward the door. Instead, it grabs in bursts. Material bunches up, then releases, then bunches again. From the seat that looks exactly like an inconsistent throttle or a door that keeps sticking. The operator makes cab adjustments that do nothing because the cause is mechanical, not procedural.
Worn flighting tips on a side discharge spreader produce a characteristic pulse pattern: ridges that repeat at roughly regular intervals, spaced according to the auger’s rotation speed. If you get off and look at a few passes, the ridges are not random. They recur at a spacing that corresponds to the auger completing one or two turns between deposits. Random ridges point toward technique. Regular, repeating ridges almost always point toward wear.
The same principle applies in mixer wagons, where clearance errors between the auger and the sidewall create wear patterns that are regularly misread as knife wear. The diagnosis logic transfers directly: look at the interval and the shape before assuming the operator is at fault.
Inspect the flighting tips by clearing the hopper and rotating the auger by hand. Worn tips will be visibly rounded or shortened compared to the un-worn sections further up the flight. A new flight tip is a consistent shallow angle. A worn one looks blunt and hesitates to bite into compacted material.
PTO RPM Versus Forward Speed: the Ridge Nobody Talks About
A PTO speed that is too low for the selected forward speed is probably the most common ridge-producing error on compact spreaders, and it rarely gets discussed because it does not cause a blockage until it is quite severe. Long before the auger stalls, the mismatch shows as ridges.
Here is the mechanism. The auger needs to be turning fast enough to keep pace with the rate at which material is being asked to discharge. If tractor forward speed is too high relative to PTO rpm, material accumulates at the door faster than the auger can move it laterally. It piles, releases in a dump, and leaves a ridge. The tractor moves on, the pile is left behind, and the cycle repeats. The operator sees a ridge roughly every five to ten metres, slows down, and the ridges shorten but do not disappear because the root cause is the rpm deficit, not the speed.
The correct sequence is: set PTO rpm first, then select a ground speed that matches it. Not the other way around. On compacted winter kraal manure, that typically means running the PTO at the manufacturer’s recommended operating speed before the door is opened, not ramping up to it after the first few metres of the pass.
It is also worth checking whether a drop in effective PTO rpm is coming from somewhere else entirely. Chain wear in the floor conveyor system or a partially blocked drive line can both reduce the power that actually reaches the expeller, even when the tractor gauge shows the right rpm. Dry, dusty late-winter conditions accelerate chain wear faster than operators often account for, and a spreader that ran fine last autumn may be working with a measurably weaker drive by the time the winter spreading programme starts. If you are working through that issue, the effect of drought conditions on spreader chain is worth a read before the season proper begins.
Reading the Ridge Before You Adjust Anything
Before touching a setting, spend five minutes reading the pattern on the pad. The shape and spacing of the ridges tell you more than the tractor display does.
- Ridges that repeat at even intervals and taper to points: flighting wear, producing pulses.
- Ridges that are wide and flat, consistent across the full pass: door opening is too wide for the ground speed.
- Ridges that worsen as the hopper empties: PTO-speed mismatch, because lighter loads reduce resistance and the auger speeds up slightly, throwing the balance off.
- A single heavy deposit at the start of a pass that clears after fifteen metres: door was already open at the start, before material was moving consistently onto the expeller.
Each of those points to a different fix. Mixing them up wastes time.
What to Check Before the Spreading Season Starts
With Mpumalanga and KwaZulu-Natal operations starting to plan spring programmes, late winter is the right time to do this inspection rather than the morning of the first load. Check flighting tip condition and measure wear against the original profile if you have a reference. Check door seal and slide mechanism for wear that would prevent repeatable settings. Verify that expeller hammers are intact and not cracked at the base. Run the empty machine at operating PTO speed and watch for any vibration that was not there last season.
LEO Agriculture’s 20 Series machines in the 1006 class use fabricated hard-faced hammers on the expeller, which extend wear life compared with flat plate alternatives. That helps, but it does not eliminate the need for inspection. Hammers crack at the mount, not at the face, and a cracked mount causes asymmetric throw that looks for all the world like a deflector shield that has shifted.
Most ridge problems on compact side spreaders are solved with a methodical walk around the machine before the first pass, not with cab adjustments during it. Set the PTO speed. Set the door opening to match your material density. Check the deflector shield is seated correctly. Then run the first ten metres, stop, and look at the pad. That one check tells you more than an hour of adjustments made while moving.
