Home Products News Contact Us
Home > Supports > Diesel Generators > Reasons for Unstable Rotational Speed of Diesel Generator

Reasons for Unstable Rotational Speed of Diesel Generator

Feb. 15, 2019

1. Idle speed is not stable


It refers to the diesel generator running at idle speed, but the regularity is not strong, and there are jitter, and diesel generator in the rapid deceleration, shift or easy to stall with load, this phenomenon is caused by the governor failure. The main causes of occurrence are the following.

Reasons for Unstable Rotational Speed of Diesel Generator.jpg


A. Fly ball wear


At idle speed, the opening degree of flying ball is the smallest, and the spring slider overreaches the flying ball because of the wear of the small roller of the ball, which results in an irregular direct collision with the fly ball body, resulting in instability of idle speed. At this point, touch the joystick with your hand, will have a slight feeling of being hit.


B. Elastic variation or improper adjustment of idle spring


When the diesel generator is in operation, the increase of load will reduce the speed. If the idle spring or start spring is softened, the feed rod can not move to the direction of increasing oil quickly to increase the speed, which will cause the diesel generator to stall automatically when serious.


C. Improper adjustment of steady speed spring


In idle operation, because of the small centrifugal force flying ball, speed control force is also small. If the diesel generator decelerates suddenly, the adjusting movement of the fuel supply rod may exceed the idle position, causing the diesel generator to stall. In order to prevent this kind of situation, the stable spring which is pushing the fuel supply tooth rod to idle position behind the governor cover; if the spring is too soft or the adjustment is biased, it will weaken or do not play a stabilizing role, making the idle speed running unstable.


D. Low pressure oil supply is poor or contains water and air


This will result in large and small fuel supply, especially in low speed regions, which will lead to unstable operation of diesel generators.


E. Excessive wear of camshaft cone bearing supported by fuel injection pump


In this case, the camshaft will cause irregular movement in the axial direction, which makes the speed of diesel generator unstable.


F. Fuel injection pump supply is uneven, fuel supply is incorrect or injection is bad.


In the case of low-speed operation, if the oil supply is not uniform or the oil supply is not correct, the stability of the rotating speed can be greatly affected, but the instability of the oil supply is regular and the periodicity is shorter.


G. Cylinder compression is insufficient


When the compression force of the cylinder decreases, the decreasing degree of each cylinder is not necessarily the same. Even if the fuel supply of the fuel injection pump is balanced, the combustion situation may still be different, resulting in the instability of the rotational speed at low speed.


2. runner wagon


The so-called “travelling vehicle” refers to the slow and slow-time phenomenon of the diesel generator in the low-speed and medium-speed range, which is the result of the excessive lag of the speed-regulating reaction to the change of the actual rotating speed. The reasons for this are the following.


A. Internal lever of governor is loosened due to wear and tear of connecting pin hole


In this case, the increase and decrease of fuel supply in the two-way speed control motion produced too much direction lag. When the engine is working, the speed regulation response must lag behind the actual speed change, but the lag should not be too large, otherwise it will produce a larger regulating amplitude. The regulating amplitude is too large, that is, when the rotational speed has increased or decreased due to the increase or decrease of the fuel supply, the fuel will continue to increase or decrease until the speed exceeds the adjusting range of the governor. Its strong feedback signal only realizes the reaction of reverse regulation through the governor, which results in the speed regulating reaction exceeding the predetermined range, which results in the phenomenon of "traveling vehicle" that the speed of speed rises and goes up and down regularly in the vicinity of a certain value.


B. Oil feed rod is not flexible enough


The fuel supply rod of fuel injection pump must be absolutely flexible to ensure the sensitivity of speed regulation reaction. Using a sensitive spring scale to test the pulling resistance of the tooth rod, the pulling resistance of the corresponding II,IV,VI,VIII cylinder injection pump should not be greater than 60,90130150g respectively. As a result of rust, deformation of plunger coupling after fastening, grinding injury of gear ring and tooth rod after plunger spring break, serious wear of shaft sleeve at the end of tooth rod, and incorrect fastening angle of fork adjusting mechanism of oil quantity. The bad installation or fit of the thrust tilting disk and the flying ball seat of the governor of the domestic fuel injection pump will affect the flexibility of the fuel feeding rod. When the resistance that affects the flexibility has not reached the degree that the oil supply tooth rod can not be moved completely, the phenomenon of "traveling car" will appear (if the oil supply tooth rod is completely unable to move, the failure phenomenon will be different depending on the stay position of the tooth rod; For example, diesel generator can not start, can not stall, speed is not controlled, flying car, etc.)


C. Improper adjustment of steady speed spring


This is similar to the improper adjustment of the steady speed spring when the idling speed is unstable. The reason for this situation is that the steady speed spring and the oil feed rod can not work flexibly together.


Contact Us
  • Add.: No. 10 Kechuang Road, High tech Zone, Nanning, Guangxi, China
  • Tel.: +86 771 5805 269
  • Fax: +86 771 5805 259
  • Cellphone: +86 134 8102 4441
                    +86 138 7819 8542
  • E-mail: sales@dieselgeneratortech.com
Follow Us

Copyright © Guangxi Dingbo Generator Set Manufacturing Co., Ltd. All Rights Reserved | Sitemap

Update cookies preferences
Contact Us