GB2129351A

GB2129351A - Exerting torque on an engine crankshaft

Info

Publication number: GB2129351A
Application number: GB08230350A
Authority: GB
Inventors: Trevor Gordon Curtis
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1982-10-25
Filing date: 1982-10-25
Publication date: 1984-05-16
Also published as: EP0107439A1

Description

1

GB 2 129 351 A 1

SPECIFICATION

Exerting torque on an engine crankshaft

This invention relates to a method of and a tool for exerting torque on an engine crankshaft. The 5 invention is particularly, but not exclusively, intended to facilitate the tightening and untightening of a bolt which secures a crankshaft pulley to the crankshaft of an engine.

This bolt is a high-torque bolt. It has to be done 10 up with a very high torque, and this makes it necessary to apply a correspondingly high torque to undo it. Complex and expensive torque-multiplication tools are known and are conventionally used for this purpose. However 15 access to this crankshaft pulley bolt is difficult and it is often not possible to use these expensive tools.

According to the present invention, there is provided a method of exerting torque on the 20 crankshaft of an engine which has a ring gear fixed on the crankshaft, in which method a pinion of smaller diameter than the ring gear is engaged with the ring gear, the pinion axis is held stationary and a controlled turning force is applied 25 to the pinion to exert the torque on the crankshaft.

In use of this method to loosen the crankshaft pulley bolt, the bolt is held by a suitable tool,

whilst torque is applied to the crankshaft through the ring gear at the opposite end of the engine 30 block. The turning force can be applied to the pinion by any suitable and convenient turning tool such as a spanner.

Because of the relative diameters of the pinion and the ring gear on the crankshaft, a considerable 35 torque-multiplication is achieved by this method.

The invention also provides a tool for exerting torque on the crankshaft of an engine, the tool having a body adapted to be secured to a housing of the crankshaft, and a pinion fixed to a shaft, the 40 shaft being journalled in the body so that the shaft can be engaged by a suitable turning tool such as a spanner whilst the pinion is engaged with a ring gear on the crankshaft of the engine.

The shaft can project through the body and can 45 carry the pinion on one side of the body and be formed at the other side in such a way that it can conveniently be engaged by a conventional turning tool.

The body may have slotted location holes 50 formed in it to permit the body to be conveniently secured to points on an engine block.

Means may be provided to lock the pinion shaft to the body.

The invention will now be further described, by 55 way of example, with reference to the accompanying drawing, in which:

Figure 1 shows diagrammatically an engine having torque applied to its crankshaft;

Figure 2 shows a tool according to the 60 invention; and

Figure 3 schematically illustrates the torque multiplication achievable by the present invention.

Figure 1 shows an engine block 1 mounted between two side members 2. The crankshaft axis is indicated by the chain dotted line 3. At one end of the crankshaft, a pulley 4 is mounted. This is bolted onto the crankshaft 3 by means of a bolt on the crankshaft axis. At the other end of the engine block 1, a starter motor is normally mounted. The starter motor has a pinion which projects through an opening in the engine block and which, when in operation, engages a ring gear 5 fixed to the crankshaft.

The tool which is shown in Figure 2 will now be described. This has a body 6. The body has a central bore and a shaft 7 which passes through this bore. A pinion 8 is keyed to one end of the shaft and the other end 9 of the shaft projects through the body 6 and has a shaped end 10. This shaped end may have an internal square drive and/or an external shape engageable by a spanner. The body 6 has slotted location holes, indicated schematically at 11, by means of which it can be secured to the engine block 1.

In use of the tool, the starter motor, which normally projects into the housing of the ring gear 5, is removed. The tool shown in Figure 2 is then applied, and the pinion 8 is introduced in place of the starter motor pinion, through an aperture in the housing and into engagement with the ring gear 5. The body 6 is then secured to the engine block 1 in a position such that the teeth of the pinion 8 remain in mesh with the teeth of the ring gear 5.

Next, a tool 12 is applied to the head of the bolt which holds the crankshaft pulley on the crankshaft. This tool is lodged against a fixed part of the engine support so as to hold the head of the bolt steady. Finally, torque is applied to the shaped end 10 of the shaft 7 to turn the shaft and the pinion 8 on the shaft, to cause the ring gear 5 to rotate. Because of the relative diameters of the pinion 8 and the ring gear 5 (as can be seen in Figure 3) a considerable multiplication of the torque applied to the shaft 7 is produced when the torque is transferred to the crankshaft 3.

Thus it can be seen that a simple and cheap tool can be provided which can allow large torques to be exerted on an engine crankshaft.

To allow the tool to be used with different engine configurations, the pinion 8 may be removable from the shaft 7 and may be interchangeable with other pinions of different sizes. The location holes 11 are slotted for the same reason, so that the body can be correctly mounted on engines having fastening points in different places. It may also be desirable to be able to lock the pinion shaft 7 relative to the body 6, and a facility for this purpose is shown at 13. This can be useful to lock the crankshaft against rotation, when access is possible to the crankshaft pulley bolt. The bolt can then be turned against a stationary shaft.

Claims

1. A method of exerting torque on the crankshaft of an engine which has a ring gear fixed on the crankshaft, in which method a pinion of

65

70

75

80

85

90

95

100

105

110

115

120

125

2

GB 2 129 351 A 2

smaller diameter than the ring gear is engaged with the ring gear, the pinion axis is held stationary and a controlled turning force is applied to the pinion to exert the torque on the crankshaft.

5 2. A tool for exerting torque on the crankshaft of an engine, the tool having a body adapted to be secured to a housing of the crankshaft, and a pinion fixed to a shaft, the shaft being journalled in the body so that the shaft can be engaged by a 10 suitable turning tool such as a spanner whilst the pinion is engaged with a ring gear on the crankshaft of the engine.

3. The tool as claimed in Claim 2, wherein the shaft extends through the body, with the pinion on 15 one side of the body and means for turning the shaft on the other side.

4. A tool as claimed in Claim 3, wherein the means for turning the shaft comprise a shaped end engageable by a turning tool.

20 5. A tool as claimed in any one of Claims 2 to 4, wherein the pinion is removable from the shaft.

6. A tool as claimed in any one of Claims 2 to 5, wherein the shaft can be locked to the body.

7. A tool as claimed in any one of Claims 2 to 6,

25 wherein the body is provided with slotted location holes by means of which it can be secured to the crankshaft housing.

8. A tool for exerting torque on the crankshaft of an engine, substantially as herein described

30 with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1984. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.