Criteria for determining and replacing the power output shaft (PTO shaft)
It is divided into five dimensions: visual inspection of appearance, no-load operation test, on load condition test, size measurement, and damage level determination. If any of them reaches the scrap standard, it is recommended to replace them directly, and repair is not recommended.
Spline area (most susceptible to damage, priority inspection)
1. It is necessary to change the situation
The spline teeth are severely worn on one side, with flat tooth tips and thinner tooth roots. When shaking the transmission shaft by hand, there is obvious looseness and radial displacement;
It is recommended to replace individual teeth with cracks, missing teeth, or falling pieces, even if a single tooth is damaged;
The spline is twisted and deformed, and under stress, it bends and cannot be smoothly inserted into the transmission shaft sleeve, resulting in lagging insertion and removal;
The depth of rust on the spline is large, and there are continuous pits. After rust removal, if the clearance exceeds the standard, the transmission will inevitably lose rotation and slip.
Simple judgment method
Put on the matching transmission sleeve, hold the outer sleeve by hand and rotate it left and right:
Slight gaps are considered normal;
The shaft body only rotates synchronously when the rotation angle exceeds 15 ° → The spline fails and needs to be replaced directly.
Deformation, bending, and cracking of the shaft body
Rotate the shaft on two parallel supports, and visible jumping and deviation with the naked eye indicate that the shaft is bent;
Visible cracks and blackened fatigue patterns appear on the shaft body, spline root, and shaft neck, which is a major safety hazard. It is highly susceptible to direct fracture under heavy load and should be replaced immediately;
There have been incidents of equipment jamming, forced starting, and failure to inspect the shaft after breaking the safety pin. These types of shafts are highly likely to have internal damage and hidden cracks, and it is recommended to replace them directly.
Oil seal matching shaft neck position (source of oil leakage)
There is a visible groove of varying depths on the surface of the shaft neck, and even after replacing the new oil seal, it still leaks oil for a short period of time and cannot be sealed;
The shaft neck is corroded, pitted, and scratched, and the oil seal lip cannot fit the sealing surface;
It is not recommended to polish or repair in such situations, as the dimensional tolerance of the shaft neck is damaged and the durability is extremely poor after repair. It is recommended to replace the shaft first.
Abnormal operation noise and damaged bearing position
When the PTO gear is idle and there are no external tools, there will be continuous buzzing and metal friction sounds;
The supporting bearings at both ends of the shaft are worn and the steps are damaged, and the bearings are loose and prone to running off the outer ring when installed;
Once the bearing position is misaligned, it is difficult to repair, and usually the output shaft assembly is replaced directly.
Fault diagnosis of load operation
After the following phenomena occur and clutch, gear, and transmission shaft problems are ruled out, the PTO shaft can be locked and scrapped:
PTO gear shifting is normal, the engine speed is increased, but the speed of the farming tools cannot be increased and is noticeably weak, accompanied by a slipping odor;
Power is intermittent during homework, occasionally losing power after bumps, mostly due to severe wear of the splines;
Once the machine is buried or loaded, it stops rotating completely. If it can rotate without load, it indicates that the shaft is internally twisted or the spline is completely ineffective.
Corrosion and jamming prevent disassembly
Long term mud and water operations in paddy fields and construction sites can lead to rusting and locking of the splines and transmission sleeves, making it impossible to disassemble and separate them. Forceful tapping can easily cause damage to the gearbox housing;
The shaft body is extensively corroded and peeled, the strength of the steel section decreases, and the torsional resistance is greatly reduced. It is recommended to replace it.
Determination of recurrence after seven repairs (not recommended for repair use)
The following situations are prone to secondary damage after repair and have no repair value:
Broken shaft welding and crack repair welding: stress concentration at the welding position increases the probability of re fracture after being subjected to stress, and may also damage the internal gears of the gearbox;
Spline welding repair: loss of fitting accuracy, large shaking, fast oil leakage, and faster wear;
Axle neck electroplating repair size: The service life is short, and the cost is not as good as directly replacing the shaft.
Grading Summary (Quick Comparison)
Can continue to be used (maintenance is sufficient)
Slight floating rust, minimal flower key clearance, no bending cracks, no grooves on the shaft neck, no abnormal noise during operation → Clean and apply grease, install dust cover and continue to use.
Maintenance observation and use
A small amount of shallow scratches, slight rust, and small gaps; After replacing the oil seal and bearing, there is no leakage or abnormal noise, which can be observed and used for a short period of time to shorten the maintenance cycle.
Forced replacement (any one that meets the requirements)
Spline teeth missing, worn out, twisted, and slipping due to excessive clearance;
The shaft is bent, visible cracks, and has been twisted and broken before;
The journal groove is worn and the oil seal is repeatedly replaced, but still leaks oil;
The installation position of the bearing is out of roundness and has serious looseness;
Power interruption failure occurs after welding repair and under heavy load conditions.
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