Interpretation ID: nht93-4.37

DATE: June 17, 1993

FROM: James N. Doan -- Counsel-Operations, Eaton Corporation

TO: John Womack -- Acting Chief Counsel, NHTSA

COPYEE: P. M. Menig

TITLE: INTERPRETATION OF FMVSS 101

ATTACHMT: Attached to letter dated 9/21/93 from John Womack to James N. Doan (A41; Std. 101)

TEXT:

Eaton Corporation manufactures and sells transmissions for heavy duty (MVMA Class 6-8) trucks. This is to request an interpretation of Federal Motor Vehicle Safety Standard Number 101, Controls and Displays (49 CFR 571.101) regarding an enhancement being considered to the mechanical controls situated at the top of the transmission shift lever for such vehicles. Specifically the issue is the necessity of illuminating a control for automated vehicle speed (cruise control) mounted on the transmission shift lever.

Presently we offer up to two pneumatic control switches for controlling an auxiliary transmission mounted integrally with the main transmission. Examples of the controls mounted on the lever in the cab of the truck are shown in Figure 1. We are considering augmenting this control with three electrical switches mounted in a housing integral with what we call the "skirt." The skirt is the plastic extending downward from the knob that covers the metal parts of the valve and creates a more aesthetically pleasing appearance. Figure 2 shows the proposed skirt with the addition of two rocker switches. One controls cruise on/off (mounted on the side face) and the other controls cruise set/resume and accelerate/coast (mounted on the slanted top face). Figure 3 shows the proposed skirt with the addition of a rotary electrical switch for controlling an engine retarder or brake. This switch has an off position and up to three levels of retardation. Extreme care has been taken to make these controls readily accessible to the driver such that they can be operated without the driver having to remove his eyes from the road. We expect the cruise switches to be used during certain shifting maneuvers, especially on long upgrades where the driver will manipulate the switches to achieve cruise control in the next lower numerical gear ratio. This is consistent with how the driver presently operates the two pneumatic switches, completely by feel. We have chosen two separate planes for the switches (side face and slanted top face) to aid the driver in differentiating the switches. Furthermore, we have put the engine brake switch on yet another face to further aid operation by feel/position. With electronically controlled engines in trucks, we expect the engine brake switch will be put in one position and left there. On/off operation will then be handled by interrupts from other switches in the cab, especially the service brake switch.

"Cut out" of the cruise control and engine brake by other cab mounted switches is an important consideration. Figure 4 is a spreadsheet of intended operation of electronic engine controls for trucks for 1994 and beyond. Note that the service brake and the clutch pedal switches can cause the engine control to cease regulating engine and vehicle speed. In any emergency situation, one of these switches is likely to be activated, stopping the cruise control mode of operation.

It would be difficult and costly to illuminate the automated vehicle speed switches. We believe that these controls are "hand operated controls mounted upon the floor ... (or) floor console" and do not require illumination as specified in S 5.3.1 of FMVSS 101. They are mounted on a shift lever, mounted on the floor next to the operator and within easy reach. We would appreciate confirmation of this interpretation.

Please let me know if you have any questions or require any further information.

(Graphics omitted.)