The tractor creeper is intended for installation on the tractors operated with the machines requiring reduced speeds of movements (reapers, snow ploughs, crop collectors, etc.).
Using the creeper makes it possible to reduce additionally the tractor speed in four gears of the first range of the forward and reverse movement each 4.5 times.
The calculated speeds of movement of the tractor with the creeper engaged are:
- in the forward movement: 0.384, 0.537, 0.738 and 1,01 km/h, respectively;
- in the reverse movement: 0.603, 0.844, 1.159, 1.587 km/h.
Should it be necessary to use the gears of the first range of the forward and reverse movement of the gearbox with their rated gearing ratios, it would be sufficient to disengage the creeper.
Construction and principle of operation
The tractor creeper is an independent easily removable assembly and designed as a planetary spur-gear speed reducer to be installed on the left of the gearbox as seen in the direction of movement of the tractor to provide the process range of the tractor movement speeds.
Kinematic diagram of the tractor creeper
Creeper: 1 – gearbox gear; 2 – planet pinion; 3 – pinion cage; 4,8 – intermediate gear of the creeper; 5-double-wheel gear; 6 – crown gear; 7 – shaft; 9 – creeper drive gear; 10 – pinion; 11 – creeper shaft; 12,13 – rod; 14 – handle; 15 – gasket; 16 – bushing.
The torque from the engine is transmitted from the gearbox gear (1) to the planet pinions (2) of the creeper pinion cage (3) through the intermediate creeper gear (4) and double-wheel gear (5) and from the pinion cage through the mesh of the planet pinions (2) with the crown gear (6) of the planetary spur-gear speed reducer. The crown gear (6) is mounted immovably in the creeper casing onto the output shaft of the planetary spur-gear speed reducer (7). The pinion (10) transmitting the torque to the gearbox reverse shaft gear (9) through the intermediate gear (8) on the output shaft (7).
Creeper interlocking mechanism:
1,4 – fork; 2,3 – pusher; 5,6,7 – gear.
To engage the tractor creeper, it is necessary, first of all, to disengage the gears (5) and (6) in the gearbox. It is achieved by moving the pusher (2) to the right to the position fixed by the spring-loaded ball. Here the fork (1) fixed on the pusher (2) disengages the gears (5) and (6) and brings the gear (5) into complete mesh with the intermediate creeper gear (8). Then the gear (7) is brought into mesh with the intermediate gear (8) by moving the pusher (3) with the fork (4) to the left to the fixed position.
Thus, the power flow from the driving gear (1) is brought to the driven one (9) of the gearbox. The interlocking mechanism excludes the possibility of simultaneous movement of both fork and, respectively, rods as well as ensures the priority of their engagement.
Set the stable idling rotational speed of the engine; the gearbox lever shall be in the neutral position.
The tractor creeper is controlled by means of the rods (1) and (2).
In the “Creeper disengaged” position, the rod (1) is lifted while the rod (2) is depressed. In the “Creeper engaged” position, the rod (1) is depressed while the rod (2) is lifted.
The engagement of the creeper is performed in two stages:
- To engage the creeper, set the minimum stable rotational speed of the engine. Move the rod (1) downwards having depressed smoothly the clutch pedal;
- Move the rod (2) (at longer distance from the operator) upwards having depressed the clutch pedal again.
To start the movement, it is necessary to shift in the necessary gear and release smoothly the clutch pedal.
Engaging the creeper does not cause the change of the tractor movement direction.
The gears of the first forward range and reverse range shall be shifted with the clutch pedal depressed and with short (20…30 s) delay of the gear disengagement.
Prior to operation of the tractor with creeper, check the oil level in the transmission. The oil level shall not be below the upper control hole of the oil level gauge scale. If necessary, add oil. To avoid breakdowns in the transmission and overheating of oil, the tractor with creeper shall be only operated in the gears of the first range of forward and reverse motion of the gearbox.
The permissible oil temperature is not more than 100°C. After every 250 running hours of the tractor with creeper, check the oil level in the transmission, absence of leakages and tightness of threaded connections.
When operating the tractor at normal speed conditions, the creeper shall be obligatorily disconnected from the gear-box (the left rod being at longer distance from the operator is depressed).
Should it be planned to use the tractor at normal speed condition, the creeper shall be removed from the tractor to avoid the premature wear of the parts.